Ref-007

Degradation and loss of habitat through urbanization, mining, improper management of grazing, recreation, invasion of nonnative plants, impoundments, water diversions and degraded water quality,

Introduced predators, such as bullfrogs, and 3) Previous overexploitation. Historically, the California red-legged frog was found in 46 counties. The range was thought to extend coastally from Sonoma County (but recently has been confirmed further north in Mendocino County) and inland from the vicinity of Redding, Shasta County, south to northwestern Baja California, Mexico. The frog has sustained a 70 percent reduction in its geographic range in California as a result of habitat loss and alteration, overexploitation, and introduction of exotic predators. Arundo impacts: Little interaction between Arundo and these factors. Overall impact metric for Arundo on California red-legged frog: Low impact, score of 3. Interaction of Arundo distribution and CA red-legged frog occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Biological and Conference Opinions for Annual Removal of Giant Reed and Tamarisk in Upper Santa Clara River Watershed, Los Angeles county, CA (File No. 2004-01540-AOA)(1-8-06-F-5). Endangered and Threatened Wildlife and Plants; Revised Designation of Critical Habitat for the California Red-Legged Frog: Final Rule. CFR Part 17 [FWS-R8-ES-2009-0089], U.S. Fish and Wildlife Service. 7.2.4 Mountain Yellow-Legged Frog (Rana muscosa) Federal status: Endangered (Southern California DPS July 2 2002), Endangered Candidate List (frogs occurring north of the Tehachapi Mountains). Critical habitat for the southern California DPS designated on September 14 2006. State status: Candidate species Arundo impact score: 4 General Ecological Needs/Habitat Affinities: Mountain yellow-legged frogs live in glaciated alpine lakes, ponds, tarns, springs, and streams. Lakes used usually have grassy or muddy margins, and adults are typically found sitting on wet rocks along the shoreline, usually where there is little or no vegetation. Field research conducted by USGS and the San Diego Zoo within the current and historic range of the mountain yellow-legged frog in the San Jacinto, San Bernardino, and San Gabriel mountains has been carried out to improve understanding of habitat preferences of this species. Results indicate that adult frogs prefer deep, long, pools with little understory and ample leaf litter. Tadpoles also were more likely to be found in pools with less understory and more leaf litter, but showed no preference for pool depth or length. They did, however, demonstrate a preference for pools with rock substrate. Mountain yellow-legged frogs have been observed in the field basking in direct sunlight, sometimes in aggregations of more than 20. It is hypothesized that frogs aggregate to reduce the surface area exposed to the air and thus reduce water loss. Suitable habitat for mountain yellow-legged frogs presumably must include appropriate basking structures Arundo impacts: Low level of Arundo impacts due to little overlap in range. Frogs are restricted to higher elevations in general. But overlap in occurrence in two areas create the potential for interaction (Los Angeles River, in the San Gabriel Mountains and Santa Ana River in San Bernardino Mountains). Frogs appear to prefer little vegetative cover- Arundo would therefore be negatively associated with prime habitat. Breeding/Life History: Breeding sites are generally located in, or connected to, lakes and ponds that do not dry up in the summer, and that are sufficiently deep not to freeze through in winter. The frogs breed in June or July. Eggs hatch within several weeks and larvae usually transform during July or August. Larvae at high elevations, or subject to severe winters, may not metamorphose until the end of their fourth summer. Adults hibernate in water during the coldest months, under ice or near shore under ledges and in underwater crevasses. Arundo impacts: Arundo may add to water stress in foothill washes shortening pool duration. Diet: Adults feed on terrestrial insects and adult aquatic insects: beetles, flies, wasps, bees, ants, true bugs, and spiders. They also consume large quantities of Yosemite toad and Pacific treefrog tadpoles and can be cannibalistic. Tadpoles graze on algae and diatoms along rocky bottoms of streams, lakes, and ponds. Arundo impacts: Limited impacts to food resources. Movement: This species has no distinct breeding migration, as adults are almost always found within two to three feet of water. In some areas, there is a seasonal movement of frogs from deeper lakes to nearby breeding areas after overwintering. Frogs typically move less than a few hundred meters. Arundo impacts: Limited impacts to movement- very localized at stream/pool edges. Status/Distribution or Historic and Current Range: Once common throughout much of southern California, the mountain yellow-legged frog has been decreasing in numbers since the 1970s. The frog lives in the Sierra Nevada Mountains of California and Nevada from southern Plumas County to southern Tulare County, at elevations mostly above 6,000 feet. A genetic study published in 2007 revealed that there are two distinct mountain yellow-legged frog species that do not overlap in range or interbreed: a northern and central Sierra Nevada species and a southern Sierra Nevada and southern California species. In southern California, only a small wild population of less than 200 individuals can be found in the San Gabriel, San Bernardino, and San Jacinto Mountains. For the first time in April 2010, scientists reintroduced its eggs to its former habitat at University of California Riverside’s James San Jacinto Mountains Reserve. Arundo impacts: The frogs have isolated small populations (Appendix B). The fact that several of the San Gabriel Mountain populations co-occur with Arundo is of concern. Impacts related to water use, shading, and the frogs’ preference for less vegetated pools indicates that Arundo is likely a minor to moderate stressor on habitat fitness. Arundo could become a more pronounced impact if it continued to increase in abundance at sites where overlap in ranges occurs. Decline and Threats: These frogs are threatened by predation by introduced trout, pesticides, environmental changes from drought and global warming, disease, and habitat degradation due to livestock grazing. More than 93 percent of northern and central Sierra Nevada populations, and more than 95 percent of southern Sierra Nevada and southern California populations, are already extinct. Arundo impacts: Little interaction with other stressors- but the species very tenuous persistence makes low to moderate levels of impacts already outlined potentially significant for the species especially for isolated southern CA populations. Overall impact metric for Arundo on mountain yellow-legged frog: Low/Moderate impact (4) Interaction of Arundo distribution and mountain yellow-legged frog occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: USGS, Mountain yellow-legged frogs reintroduced to wild 4/16/2010. Mountain Yellow-legged Frog Update, Mountain Yellow-legged Frog Captive Breeding 2009 Annual Report, San Diego Zoo. Species Profile for the Mountain Yellow-Legged Frog, U.S. Fish & Wildlife Service. 7.2.5 Western Snowy Plover (Charadrius alexandrinus nivosus) Federal status: Threatened, March 1993. Critical habitat designated September 2005. Recovery Plan published in 2007. State status: Species of special concern Arundo impact score: 5 General Ecological Needs/Habitat Affinities: The Pacific coast population of the western snowy plover breeds primarily above the high tide line on coastal beaches, sand spits, dune-backed beaches, sparsely-vegetated dunes, beaches at creek and river mouths, and salt pans at lagoons and estuaries. This habitat is unstable because of unconsolidated soils, high winds, storms, wave action, and colonization by plants. Less common nesting habitats include bluff-backed beaches, dredged material disposal sites, salt pond levees, dry salt ponds, and river bars. In winter, western snowy plovers are found on many of the beaches used for nesting as well as on beaches where they do not nest, in man-made salt ponds, and on estuarine sand and mud flats. Arundo impacts: Arundo is typically not abundant in beach and estuary habitats (although it can develop into large stands if left to persist there). The major impacts from Arundo are related to biomass accumulating in these areas. Additionally there may be impacts to sediment transport (Chapter 5) which could be effecting beach and estuaries. These impacts are speculative but possible given Arundo strong effect of fluvial and processes. Plovers have strong preference for river mouths and estuaries in comparison to beach areas along bluffs (Appendix B). Breeding/Life History: The Pacific coast population of the western snowy plover breeds primarily on coastal beaches from southern Washington to southern Baja California, Mexico. Nesting western snowy plovers at coastal locations consist of both year-round residents and migrants. Migrants begin arriving at breeding areas in central California as early as January, although the main arrival is from early March to late April. Since some individuals nest at multiple locations during the same year, birds may continue arriving through June. In California, pre-nesting bonds and courtship activities are observed as early as mid-February. Eggs are laid in scrapes (depression in the sand or other substrate created by the male). The earliest nests on the California coast occur during the first week of March in some years and by the third week of March in most years. Peak initiation of nesting is from mid-April to mid-June. Nests typically occur in flat, open areas with sandy or saline substrates; vegetation and driftwood are usually sparse or absent. In southern California, western snowy plovers nest in areas with 6 to 18 percent vegetative cover and 1 - 14 % inorganic cover; vegetation height is usually less than six centimeters (2.3 inches). Nests consist of a shallow scrape or depression, sometimes lined with beach debris (e.g., small pebbles, shell fragments, plant debris, and mud chips); nest lining increases as incubation progresses. Driftwood, kelp, and dune plants provide cover for chicks that crouch near objects to hide from predators. Although driftwood is an important component of western snowy plover habitat, too much driftwood on a beach, which may occur after frequent and prolonged storm events, can be detrimental if there is not sufficient open habitat to induce the birds to nest. In southern California nests are usually located within 328 ft (100 m) of water, which could be either ocean, lagoon, or river mouth. Invertebrates are often found near debris, so driftwood and kelp are also important for harboring western snowy plover food sources. Hatching lasts from early April through mid-August, with chicks reaching fledging age approximately one month after hatching. Fledging of late-season broods may extend into the third week of September throughout the breeding range. Arundo impacts: Arundo biomass significantly degrades nesting habitat by covering open sandy substrate. Additional impacts are outlined in FWS BO's: In some areas of California, such as the Santa Margarita River in San Diego County, and the Santa Clara and Ventura Rivers in Ventura County, giant reed has become a problem along riparian zones. During winter storms, giant reed is washed downstream and deposited at the river mouths where western snowy plovers nest. Large piles of dead and sprouting giant reed eliminate nesting sites and increase the presence of predators, which use it as perches and prey on rodents in the piles of vegetation. Diet: Western snowy plovers are primarily visual foragers, using the run-stop-peck method of feeding. They forage on invertebrates in the wet sand and amongst surf-cast kelp within the intertidal zone, in dry sand areas above the high tide, on salt pans, on spoil sites, and along the edges of salt marshes, salt ponds, and lagoons. They sometimes probe for prey in the sand and pick insects from low-growing plants. Western snowy plover food consists of immature and adult forms of aquatic and terrestrial invertebrates. Arundo impacts: Arundo debris and stands reduce habitat quality for food (invertebrates); impacts feeding as well as foraging for prey. Movement: While some western snowy plovers remain in their coastal breeding areas year-round, others migrate south or north for winter. In Monterey Bay, California, 41 % of nesting males and 24 % of the females were consistent year-round residents. At Marine Corps Base Camp Pendleton in San Diego County, California, about 30 % of nesting birds stayed during winter. The migrants vacate California coastal nesting areas primarily from late June to late October. Arundo impacts: Arundo debris piles limit movement of young. Status/Distribution or Historic and Current Range: The Pacific coast population is defined as those individuals that nest within 50 miles of the Pacific Ocean on the mainland coast, peninsulas, offshore islands, bays, estuaries, or rivers of the United States and Baja California, Mexico. By the late 1970s, nesting western snowy plovers were absent from 33 of 53 locations with breeding records prior to 1970. By 2000 populations had declined further to 71 % of the 1977-1980 levels along the California coast and 27 % of the 1977-1980 levels in San Francisco Bay. However, since then populations have grown substantially, roughly doubling along the coast while fluctuating irregularly in San Francisco Bay. Recent population increases along the coast have been associated with implementation of management actions for the benefit of western snowy plovers and California least terns, including predator management and protection and restoration of habitat. Arundo impacts: Arundo is abundant on several key watersheds that support plover populations (Appendix B). Decline and Threats: Habitat degradation caused by human disturbance, urban development, introduced beachgrass (Ammophila spp.), and expanding predator populations have resulted in a decline in active nesting areas and in the size of the breeding and wintering populations. Arundo impacts: As indicated Arundo stands are correlated with predation as predators use stands for perching in nesting areas. Overall impact metric for Arundo on the Western snowy plover: Moderate, score of 5. Interaction of Arundo distribution and the Western snowy plover’s occurrence is presented by watershed in Table 7-3. Sources: Recovery Plan for Pacific Coast Population of the Western Snowy Plover, USFWS, 2001 http://www.fws.gov/arcata/es/birds/WSP/documents/RecoveryPlanWebRelease_09242007/WSP%20F inal%20RP%2010-1-07.pdf Powell, A.N., J.M. Terp, C.L. Collier, and B.L. Peterson. 1997. The status of western snowy plovers (Charadrius alexandrinus nivosus) in San Diego County, 1997. Report to the California Department of Fish and Game, Sacramento, CA, and U.S. Fish and Wildlife Service, Carlsbad CA, & Portland OR. 7.2.6 Western Yellow-Billed Cuckoo (Coccyzus americanus) Federal status: Species of Concern State status: Endangered Arundo impact score: 7 General Ecological Needs/Habitat Affinities: Western yellow-billed cuckoos typically inhabit densely foliated, stands of deciduous trees and shrubs, particularly willows, with a dense understory formed by blackberry, nettles, and/or wild grapes, adjacent to slow-moving watercourses, backwaters, or seeps. River bottoms and other mesic habitats, including valley-foothill and desert riparian habitats, are necessary for breeding. Dense low-level or understory foliage with high humidity is preferred. Field studies and habitat suitability modeling have concluded that vegetation type (e.g., willow scrub and cottonwood-willow forest), patch size, patch width, and distance to water are important factors determining the suitability of habitat for yellow-billed cuckoo breeding. Patch size is an important variable determining presence of cuckoos in California, with a trend toward increasing occupancy with increased patch size. Few cuckoos have been found in forested habitat of less than 25 acres. Willow-cottonwood habitat patches greater than 1,970 ft (600 m) in width were found to be optimal, and typically anything less than 328 ft (100 m) is unsuitable. Arundo impacts: Arundo and cuckoos both prefer broad river bottoms creating a significant interaction between the species. Cuckoos prefer well-developed riparian habitat that is dense with large gallery trees. Arundo displaces native vegetation and fires generate create younger serial stages that cuckoos do not prefer or utilize as habitat. Breeding/Life History: Western cuckoos breed in large blocks of riparian habitats, particularly woodlands with cottonwoods (Populus fremontii) and willows (Salix spp.). Dense understory foliage appears to be an important factor in nest site selection, while cottonwood trees are an important foraging habitat in areas where the species has been studied in California. Clutch size is usually two or three eggs, and development of the young is very rapid, with a breeding cycle of 17 days from egg-laying to fledging of young. Although yellow-billed cuckoos usually raise their own young, they are facultative brood parasites, occasionally laying eggs in the nests of other yellow-billed cuckoos or of other bird species. Males and females reach sexual maturity the first year after hatching. Chicks are able to fly between 17 and 21 days after hatching and within a few weeks will migrate to South America. Arundo impacts: Arundo significantly degrades habitat by impacting lager mature trees (fire) and displacing the dense native understory vegetation. Arundo fragments and degrades riparian habitat through fire and swaths of low value habitat isolating higher quality patches. Diet: More than 75 % of the yellow-billed cuckoo’s diet is comprised of grasshoppers and caterpillars, though the species has been known to eat other insects such as beetles, cicadas, wasps, flies, katydids, dragonflies, and praying mantids. Arundo impacts: Arundo provides none of the preferred food sources and displaces native vegetation- particularly native willows and cottonwoods that are habitat for mourning cloak butterfly and caterpillars. Movement: Cuckoos leave North America in August and head to their wintering grounds in northwestern Costa Rica, Panama, and west of the Andes in Columbia, Ecuador, and Peru. It is believed that western cuckoos migrate primarily to southern Central America, remaining along the Pacific, and down into northwestern South America, remaining west of the Andes. Arundo impacts: No impact to migration. Movement within habitat is impacted. Status/Distribution or Historic and Current Range: Yellow-billed cuckoos occur in the western United States as a distinct population segment (DPS). The area for this DPS is west of the crest of the Rocky Mountains. In California prior to the 1930s, the species was widely distributed in suitable river bottom habitats, and was locally common. It is estimated that in California the species’ range is now about 30 % of its historical extent. Studies since the 1970s indicate that there are fewer than 50 breeding pairs in all of California. Given that only Santa Ana and Santa Clara have had reported sightings since 1989, it is possible that the species may become or is already functionally extirpated from Southern California. Sightings may be individuals migrating to the South Fork of the Kern River or the Sacramento River. Arundo impacts: Arundo is abundant on the two watersheds with cuckoo occurrence data collected since 1989; all other occurrence data is from the 1970s or late 1800s/early 1900s (Los Angeles region- Appendix B). Decline and Threats: Adequate patch size and loss of habitat are the primary threats to western yellow-billed cuckoo populations. Principal causes of riparian habitat losses are conversion to agricultural and other uses, dams and river flow management, stream channelization and stabilization, and livestock grazing. Available breeding habitats for cuckoos have also been substantially reduced in area and quality by groundwater pumping and the replacement of native riparian habitats by invasive non-native plants, particularly tamarisk and Arundo. Fragmentation effects include the loss of patches large enough to sustain local populations, leading to local extinctions, and the potential loss of migratory corridors, affecting the ability to recolonize habitat patches. Much of the catastrophic decline of the cuckoo in California has been directly attributed to breeding habitat loss from clearing and removal of huge areas of riparian forest for agriculture, urban development and flood control (see chapter 5.3- historic trends of geomorphology, particularly the loss of terraces, where mature gallery forest would occur). Another likely factor in the loss and modification of the yellow-billed cuckoo is the invasion by exotic tamarisk (Tamarisk spp.) and Arundo. The spread and persistence of tamarisk and Arundo has resulted in significant changes in riparian plant communities. In monotypic tamarisk and Arundo stands, the most striking change is the loss of community structure. The multi-layered community of herbaceous understory, small shrubs, middle-layer willows, and over-story deciduous trees is often replaced by one monotonous layer. Plant species diversity has declined in many areas and relative species abundance has shifted in others. Other effects include changes in percent cover, total biomass, fire cycles, thermal regimes, and perhaps insect fauna. Conversion to tamarisk or Arundo typically coincides with reduction or complete loss of bird species strongly associated with cottonwood-willow habitat including the yellow-billed cuckoo Overall impact metric for Arundo on the Western yellow-billed cuckoo: High impact, score of 7. Interaction of Arundo distribution and the Western yellow-billed cuckoo’s occurrence is presented by watershed in Table 7-3 and Appendix B. Note that although there is high impact to habitat function for the species- the species is only present as 'historic occurrences' on most watersheds. Santa Ana and Santa Clara still have periodic sightings. These watersheds score high in relative abundance: there are not many sightings but these are a large proportion of sightings for the species. It is not locally abundant anywhere. Sources: U.S. Fish and Wildlife Service Species Assessment and Listing Priority Assignment Form for: Coccyzus americanus (Yellow-billed Cuckoo), Western United States Distinct Population Segment. http://ecos.fws.gov/docs/candforms_pdf/r8/B06R_V01.pdf Stillwater Sciences. 2007. Focal Species Analysis and Habitat Characterization for the Lower Santa Clara River and Major Tributaries, Ventura County, California. Santa Clara River Parkway Floodplain Restoration Feasibility Study. 7.2.7 Southwestern Willow Flycatcher (Empidonax trailii extimus) Federally status: Endangered, February 1995. Critical habitat designated October 2005. Final recovery plan completed August 2002. State status: Endangered, January 1991. Arundo impact score: 8 General Ecological Needs/Habitat Affinities: The southwestern willow flycatcher occurs in riparian woodlands along streams and rivers with mature, dense stands of willows (Salix spp.), cottonwoods (Populus spp.), or smaller spring fed areas with willows or alders (Alnus spp.). Riparian habitat is used for both foraging and breeding. Suitable habitat typically consists of the following habitat features: 1) Nesting habitat with trees and shrubs that include, but are not limited to, willow (Salix spp.) species and boxelder (Acer negundo), 2) Nesting habitat with a dense (i.e., 50- 100 %) tree and/or shrub canopy, 3) Dense riparian vegetation with thickets of trees and shrubs, 4) Dense patches of riparian forest interspersed with small areas of open water or marsh, creating a mosaic; patch size may be as small as 0.25 ac or as large as 175 ac. Arundo impacts: Arundo displaces native vegetation forming monotypic stands or co-occurring with native woody vegetation. Both of these situations degrade habitat value. Abiotic system changes caused by Arundo related to fire and more frequent flooding degrade habitat value by creating more areas with early serial stages. Breeding/Life History: Nests are typically placed in even-aged, structurally homogeneous and dense plant communities. They usually nest in the upright fork of a shrub, but occasionally nest on horizontal limbs within trees and shrubs. Historically the flycatcher nested primarily in willows and mulefat (Baccharis salicifolia) with a scattered overstory of cottonwood. With changes to riparian plant communities, they still nest in willows where available, but are also known to nest in thickets dominated by the non-native shrub tamarisk (Tamarix species) and Russian olive (Elaeagnus angustifolia). Males typically arrive in California at the end of April and females arrive approximately one week later. They have a home range that is larger than the defended territory. Territorial defense usually begins in late May. Territory size varies from 0.25 to 5.7 acres, with most in the range between 0.5 and 1.2 aces. They typically raise one brood per year, with a clutch size usually 3-4. The fledglings leave the nest at age 12-15 days in early July, and usually disperse from the natal territory at age 26-30 days. In southern California flycatchers usually leave the breeding grounds by the end of August, and it is exceeding scarce in the United States after mid-October. Arundo impacts: Arundo degrades habitat quality as it displaces vegetation with suitable nesting structure. Diet: The southwestern willow flycatcher is an insectivore that forages within and above dense riparian vegetation, taking insects on the wing or gleaning them from foliage. They may also forage in areas adjacent to nest sites which may be more open. They are active diurnally. Arundo impacts: Arundo appears to have little foraging value for the southwestern willow flycatcher as it supports a reduced diversity and abundance of aerial insects compared to native vegetation (Herrera & Dudley 2003). Arundo displaces vegetation that supports food species. Movement: Males usually arrive in California at the end of April, and females about a week later. They generally leave in August. The migration routes and destination of the willow flycatcher are not well known. The flycatcher most likely winters in Mexico, Central America and perhaps northern South America, however, the habitat is uses as wintering grounds are unknown. Arundo impacts: No impact to migration- but Arundo interferes with movement within the territory- obstructing access to lower canopy and impeding foraging. Status/Distribution or Historic and Current Range: Current estimated distribution of the southwestern willow flycatcher in California is shown in Figure 7- 16/19. The current breeding range includes southern California, southern Nevada, Arizona, New Mexico and western Texas. The historic range in California apparently included all lowland riparian areas of the southern third of the state. In the 1930 it was considered a common breeder in coastal southern California, but it declined precipitously over the last 50 years or so. Arundo impacts: Arundo is abundant on two specific watersheds with large numbers of flycatchers (Table 7-3, Appendix B). One watershed has moderate interaction/overlap in distribution and eight watersheds have slight interaction. The species has a wide distribution but low populations on most watersheds. Decline and Threats: The major threats to the flycatcher are the destruction, modification, or curtailments of habitat, and nest parasitism by cowbirds. Loss and modification of riparian habitat has occurred due to urban and agricultural development, water diversion and impoundments, channelization, livestock grazing, off- road vehicle and other recreational uses, and hydrological changes resulting from these and other land uses. Overall impact metric for Arundo on southwestern willow flycatcher: Very high impact, score of 8. Interaction of Arundo distribution and southwestern willow flycatcher occurrence is presented by watershed in Table 7-3 and illustrated in Appendix B. Sources: U.S. Fish and Wildlife Service. 2002. Southwestern Willow Flycatcher Recovery Plan. Albuquerque, New Mexico. http://ecos.fws.gov/docs/recovery_plans/2002/020830c.pdf Stillwater Sciences. 2007. Focal Species Analysis and Habitat Characterization for the Lower Santa Clara River and Major Tributaries, Ventura County, California. Santa Clara River Parkway Floodplain Restoration Feasibility Study. 7.2.8 Belding's Savannah Sparrow (Passerculus sandwichensis beldingi) Federal status: Species of Concern State status: Endangered, 1974. Arundo impact score: 2 General Ecological Needs/Habitat Affinities: Belding’s are ecologically associated with dense pickleweed, particularly Sarcocornia pacifica (formerly Salicornia virginica), within which most nests are found. Arundo impacts: Arundo is not typically abundant in estuaries although it can occur there. Of more concern is biomass from upstream sources that accumulates in estuaries. Most of the estuaries where the sparrows occur are connected to smaller stream order riverine systems. Less Arundo is found on these size systems. Arundo impacts to system hydrology and geomorphic processes could be of concern in certain situations- sediment loads, biomass blocking flows. But these impacts are probably less on the size river systems that support sparrow habitat in estuaries. Breeding/Life History: Breeding territories can be very small and they nest semi-colonially or locally concentrated within a larger block of habitat, all of which may appear generally suitable. Arundo impacts: Minimal impact. Diet: Feeds mostly on the ground (seeds), generally alone or, during the non-breeding season, in small flocks. Arundo impacts: Minimal impact. Movement: They remain within the salt marsh year round. Arundo impacts: Minimal impact. Status/Distribution or Historic and Current Range: Based upon the 2010 surveys, Belding’s sparrows are doing well within their range in California but particularly at Point Mugu, Seal Beach National Wildlife Refuge (NWR), Bolsa Chica, Upper Newport Bay, Sweetwater Marsh NWR, and Tijuana Slough NWR. This is associated in part with the levels and quality of hands-on efforts at these wetlands. For example, Point Mugu has one of the most active and successful Natural Resources Management programs of any of the coastal wetlands in the southern California Bight. At San Elijo and Los Peñasquitos Lagoons the ocean inlets are being monitored and kept open as much as possible. This often minimizes flooding and hyper-saline conditions that greatly reduce Belding’s sparrows nesting success. Arundo impacts: There is interaction between sparrow and Arundo distributions. Arundo occurs within occupied habitat in a few areas, but as noted it is not abundant in estuaries. Arundo debris is not mapped, but is predicted based on abundance of Arundo upstream of occupied sites. Many of the occupied estuaries are on smaller lower energy systems so significant Arundo biomass inputs are not likely. Calleguas Watershed is a noted potential exception but much of the estuary complex is not well connected to the river mouth. This partly protects it from Arundo debris being pulled back into the estuary complex after it has been dispersed into the ocean or from deposition as debris racks during flow events. Decline and Threats: Over 75% of the coastal wetland habitats within this range have been lost or highly degraded and the remainder suffer from the effects of increasing human populations. Overall impact metric for Arundo on the Belding’s savannah sparrow: Very low impact, score of 2. Interaction of Arundo distribution and the Belding’s savannah sparrow’s occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: A Survey of the Belding’s Savannah Sparrow in California 2010, State of California, The Resources Agency, Department of Fish and Game Wildlife Branch. Prepared by Richard Zembal and Susan M. Hoffman, Clapper Rail Recovery Fund, Huntington Beach Wetlands Conservancy, September 2010. 7.2.9 Coastal California Gnatcatcher (Polioptila californica californica) Federal status: Threatened, March 1993. Critical habitat (Revised) designated December 2007. State status: None? Arundo impact score: 2 General Ecological Needs/Habitat Affinities: The range and distribution of the gnatcatcher is closely aligned with coastal scrub vegetation. This vegetation is typified by low (<1m), shrub and sub-shrub species that are often drought deciduous. The coastal scrub plant communities that overlap the range of the gnatcatcher include Venturan, Diegan, and Riversidean coastal sage scrub (CSS) communities, and Martirian and Vizcainan coastal succulent scrub communities. Gnatcatchers may also occur in other nearby plant communities, especially during the non-breeding season, but gnatcatchers are closely tied to coastal scrub for reproduction. Arundo impacts: Arundo is not typically found in coastal sage scrub, but CSS habitat and riparian zones are closely aligned in most areas along the coast. Impacts related to fire, both fires starting in Arundo and Arundo contributions to wildland fires, can have impacts to adjacent habitat. Fire impacts to CSS can result in both direct take of the species as well as degradation of habitat (short term functional loss, and potentially long term degradation- dependent on fire history and recovery of site). Gnatcatchers are also year round residents and riparian vegetation offers refuge and food resources in late summer/fall/winter when coastal sage scrub is less productive. Breeding/Life History: The gnatcatcher is non-migratory and defends breeding territories ranging in size from 1 - 6 hectares (2 - 14 acres). The home range size of the gnatcatcher varies seasonally and geographically, with winter season home ranges being larger than breeding season ranges and inland populations having larger home ranges than coastal. The breeding season of the gnatcatcher generally extends from late February through July (sometimes later), with the peak of nest initiations occurring from mid-March through mid- May. Nests are composed of grasses, bark strips, small leaves, spider webs, down, and other materials and are often located in California sagebrush (Artemisia californica) plants about 1 m above the ground. The incubation and nestling periods encompass about 14 and 16 days, respectively. Arundo impacts: No impact except those related to fire. Diet: California gnatcatchers are ground and shrub-foraging insectivores. They feed on arthropods, beetles, spiders, leafhoppers, and other small insects. Most of their water intake is obtained through their diet. Arundo impacts: Little impact-although riparian areas can be used for foraging during times of low productivity in CSS, and high Arundo cover degrades this function. Movement: The gnatcatcher is non-migratory. Dispersal of juveniles generally requires a corridor of native vegetation that provides certain foraging and sheltering requisites and that connects to larger patches of appropriate sage scrub vegetation. These dispersal corridors facilitate the exchange of genetic material and provide a path for re-colonization of extirpated areas. The gnatcatcher generally disperses short distances through contiguous, undisturbed habitat, but juvenile gnatcatchers are capable of dispersing long distances (up to 22km/14 mi) across fragmented and highly disturbed sage scrub habitat, such as that found along highway and utility corridors or remnant mosaics of habitat adjacent to developed lands. Arundo impacts: No impact. Status/Distribution or Historic and Current Range: The range of the gnatcatcher is coastal southern California and northwestern Baja California, Mexico, from southern Ventura and San Bernardino Counties, California, south to approximately El Rosario, Mexico, at about 30 degrees north latitude. Arundo impacts: See Appendix B. Decline and Threats: The main threat to the coastal California gnatcatcher is habitat loss, fragmentation, and degradation. Urban and agricultural development, livestock grazing, invasion of exotic grasses, off-road vehicles, pesticides, and military training activities all contribute to the destruction of gnatcatcher habitat. Overall impact metric for Arundo on the coastal California gnatcatcher: Very low impact, score of 2. If wildland fires were documented to have greater extent due to presence of Arundo stands in core gnatcatcher upland areas this score should be elevated. Significant take and/or long term degradation would occur to upland habitat. Interaction of Arundo distribution and the coastal California gnatcatcher’s occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Coastal California Gnatcatcher Five Year Review, U.S. Fish and Wildlife Service, Carlsbad, CA. September 2010. http://ecos.fws.gov/docs/five_year_review/doc3571.pdf 7.2.10 Light Footed Clapper Rail (Rallus longirostris levipes) Federal status: Endangered, October 1970. No critical habitat designated. State status: Endangered, June 1971 Arundo impact score: 3 General Ecological Needs/Habitat Affinities: The light-footed clapper rail uses coastal salt marshes, lagoons, and their maritime environs. Nesting habitat includes tall, dense cordgrass (Spartina foliosa) and occasionally pickleweed (Sarcocornia pacifica – formerly Salicornia virginica) in the low littoral zone, wrack deposits in the low marsh zone, and hummocks of high marsh within the low marsh zone. Fringing areas of high marsh serve as refugia during high tides. Although less common, light-footed clapper rails have also been observed to reside and nest in freshwater marshes. Activities of the light-footed clapper rail are tide-dependent. They require shallow water and mudflats for foraging, with adjacent higher vegetation for cover during high water. They forage in all parts of the salt marsh, concentrating their efforts in the lower marsh when the tide is out, and moving into the higher marsh as the tide advances. Arundo impacts: Arundo does not occur in the lower estuary habitat that rails use. However, biomass of Arundo from upstream stands can be deposited in estuaries (relevance is tied to abundance of Arundo on a given system). Also, larger order systems that are significantly invaded may have significant modification of flow dynamics, sediment transport, and hydrology which may affect quality of estuary habitat at the river mouth (if estuaries are still connected to the river system). Breeding/Life History: Nesting usually begins in March and late nests hatch by August. Nests are placed to avoid flooding by tides, yet in dense enough cover to be hidden from predators and to support the relatively large nest. Potential predators on eggs, nestlings, or adults include California ground squirrels, old world rats, striped skunk, feral house cats, dogs, gray fox, red fox, Virginia opossum, and raptors. Arundo impacts: Arundo harbors a range of mammals and predators that use the physical structure. Diet: Light-footed clapper rails are omnivorous and opportunistic foragers, which rely mostly on salt marsh invertebrates such as beetles, garden snails, California horn snails, salt marsh snails, fiddler and hermit crabs, crayfish, isopods, and decapods. Arundo impacts: No impact. Movement: The light-footed clapper rail is resident in its home marsh except under unusual circumstances. Within- marsh movements are also generally confined and usually of no greater spread than 1,312 feet (400m). However, a banded captive-bred female rail which was released at Point Mugu in August of 2004 was found in December of 2004 at Upper Newport Bay, a distance of 145 km (90 mi) along the coast. Minimum home range sizes for nine clapper rails that were radio-harnessed for telemetry at Upper Newport Bay varied from approximately 0.8 - 4.1 acres. The larger areas and daily movements were by first year birds attempting to claim their first breeding territories. Arundo impacts: No impact. Status/Distribution or Historic and Current Range: The historical range of the light-footed clapper rail was originally described as extending from Santa Barbara County, California to San Quintin Bay, Baja California, Mexico. In the early 1900s, ornithologists noted a decrease in the abundance of rails and observed that they were no longer found in areas, which were formerly occupied. Since 1900, 75 %of the coastal estuaries and wetlands in southern California have been destroyed or adversely modified. Light-footed clapper rails have not been detected in Santa Barbara County since 2004 or in Los Angeles County since 1983. The range in California now extends from Ventura County in the north to the Mexican border in the south. Arundo impacts: Rails occur in estuaries of both large and small watershed systems- particularly in San Diego County (Appendix B). Rails can extend fairly far into the watershed (where pickleweed occurs), but some of these are historic records. Arundo is abundant on some of these watersheds. Decline and Threats: Continued loss and degradation of salt marsh habitat. Overall impact metric for Arundo on the light-footed clapper rail: Low impact, score of 3. Interaction of Arundo distribution and the light footed clapper rail’s occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Light-footed Clapper Rail Five Year Review, U.S. Fish and Wildlife Service, Carlsbad, CA. August 2009. http://ecos.fws.gov/docs/five_year_review/doc2573.pdf 7.2.11 California Least Tern (Sterna antillarum browni) Federal status: Endangered June 2, 1970. Final Recovery Plan 1980, revised 1985. State status: Endangered, June 27, 1971. Arundo impact score: 4 General Ecological Needs/Habitat Affinities: California least terns nest on beaches, usually choosing locations in an open expanse of light-colored sand, dirt or dried mud close to a lagoon or estuary with a dependable food supply. Formerly, sandy open beaches were used, but human activity on beaches has forced terns to nest on mud and sand flats back from the ocean, and on man-made habitats. In addition to nesting areas, California least terns also require secure roosting and foraging areas. Roosting areas are of two kinds: pre-season nocturnal roosts and post-season dispersal sites where adults and fledglings congregate. Terns forage primarily in nearshore ocean waters and in shallow estuaries and lagoons. Arundo impacts: Arundo is not abundant in the beach and estuary habitat- but there can be locally occurring stands and occurrences of the plant. Arundo debris and to a lesser degree hydrologic and geomorphic alteration of river systems can have impacts on terns. Breeding/Life History: Most least terns begin breeding in their third year. Mating begins in April or May. The nest is a simple scrape in the sand and may be lined with shell fragments, pebbles, twigs. Typically there are 2 eggs. Both parents incubate and care for the young. They can re-nest up to two times if eggs or chicks are lost early in the breeding season. Nesting season extends from approximately May 15 into early August, with the majority of nests completed by mid June. A second wave of nesting occurs from mid-June to early August. These are mainly re-nests after initial failures, and second year birds nesting for the first time. Predators of the California least tern are larger birds, mammals such as raccoons and foxes, and domestic dogs and cats. Arundo impacts: Most tern breeding areas are nearly devoid of vegetation and plant debris (observation of nesting sites in San Diego and Ventura Counties). Arundo debris and live plant structure is a degradation of habitat. Debris reduces useable area. Any structure fosters predation from birds and any concealment encourages predatory mammals. Diet: California least terns eat small fish. Arundo impacts: No impact. Movement: The California least tern is migratory, usually arriving in its breeding area by mid April and departing again in August. However, terns have been recorded in the breeding range as early as March 13 and as late as October 31. Adult terns move south along the California coast with their fledglings in the autumn, stopping to rest and feed along the migration route. Arundo impacts: No impact. Status/Distribution or Historic and Current Range: Historically California least terns nesting in large colonies spread along undisturbed beaches. However with development of the California coast and fragmentation of large beach areas, birds now nest in the small fragments of habitat remaining in the same general areas. The nesting range in California is discontinuous, with large colonies spread out along beaches at estuaries. The northern limit for nesting is San Francisco Bay, and the southern limit is in Baja California, Mexico. Today the tern is concentrated in three southern California counties: Los Angeles, Orange and San Diego. Arundo impacts: Arundo is abundant on several watersheds in Orange and San Diego Counties (Appendix B). Decline and Threats: California least terns were apparently once abundance and well distributed on barrier beaches and beach strand along the southern California coast. The reduction in tern numbers was apparently gradual and associated with human population increases in the area. The species was noted as seriously declining within its range before the 1930s. Today the tern is concentrated in three southern California counties: Los Angeles, Orange and San Diego. Since 1973 there has been on overall increase in least tern in California due to recovery efforts such as site management and protection of known nesting sites (fencing, predator control, monitoring, research). Decline of the California least tern is due to loss and degradation of beach habitat, impacts and disturbance from human and domestic animal use of beaches, and loss and fragmentation of wintering habitat. Overall impact metric for Arundo on the coastal California least tern: Low/Moderate, score of 4. Interaction of Arundo distribution and the coastal California least tern’s occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: California Least Tern Five Year Review Summary and Evaluation, U.S. Fish and Wildlife Service, Carlsbad, CA. September 2006. http://ecos.fws.gov/docs/five_year_review/doc775.pdf Revised California Least Tern Recovery Plan, U.S. Fish and Wildlife Service, Portland, Oregon. April 1980. http://ecos.fws.gov/docs/recovery_plan/850927_w%20signature.pdf 7.2.12 Least Bell's Vireo (Vireo bellii pusillus) Federal status: Endangered, May 1986. Critical habitat designated February 1994. Draft recovery plan completed in 1998. State status: Endangered, October 1980. Arundo impact score: 9 General Ecological Needs/Habitat Affinities: Least Bell’s vireo is a small, olive-grey migratory songbird that nests and forages almost exclusively in riparian woodland habitats. Primary constituents of critical habitat for the vireo include riverine and floodplain habitat, and adjacent coastal sage scrub, chaparral, or other upland communities. Nesting habitat typically consists of well-developed overstories and understories, and low densities of aquatic and herbaceous cover. The understory frequently contains dense subshrub or shrub thickets. These thickets are often dominated by sandbar willow (Salix hindsiana), mulefat (Baccharis salicifolia), young individuals of other willow species, such as arroyo willow (Salix lasiolepis) or black willow (Salix gooddingii), and one or more herbaceous species. Important overstory specie include mature arroyo willow and black willows; occasional cottonwoods (Populus spp.) and western sycamores (Platanus racemosa) occur in some habitats. Additionally, coast live oak (Quercus agrifolia) can be a locally important overstory component, as can mesquite (Prosopis spp.). Arundo impacts: Arundo and vireos prefer the same broad coastal riparian habitat types. Significant impacts from abiotic modification of the riverine system impact ecosystem to the detriment of the vireo. There changes include fire, geomorphic impacts that interfere with vegetation succession, and outright displacement of vegetation that vireos are dependent on. Direct take and long term degradation of habitat occurs after fires initiating in Arundo stands as well as wildland fires that are larger are more intense when Arundo is present. Breeding/Life History: Following pair formation, it takes approximately 5 - 7 days for them to finish nest construction and egg laying. Young typically fledge within 20 - 24 days after eggs are laid. The egg laying and incubation periods are critical to the nesting success, as disturbance at this point may result in abandonment of the nest. Arundo impacts: Arundo displaces native vegetation reducing available habitat for nesting. Arundo does not have suitable structure for vireo nests. Diet: They are almost exclusively insectivorous, and forage in riparian woodland and suitable adjacent upland habitat. Arundo impacts: Arundo support a low abundance and diversity of insects, particularly in comparison to native vegetation (Herrera & Dudley 2003, Going & Dudley 2008). Vireos are rarely seen feeding on Arundo as the plants has few insects that directly feed on it. Birds are rarely seen feeding in Arundo. Movement: Least Bell’s vireos generally begin to arrive from their wintering range in southern Baja California and establish breeding territories by mid- to late March. Most breeding vireos depart by the third week of September and only a very few individuals are found wintering in California. Most vireos occupy home ranges that are typically from 0.5 - 4.5 acres, but a few may be as large as 7.5 acres. Once the young are fledged they wander widely throughout the parents’ territory. Arundo impacts: Arundo stands inhibit movement of avian species as the feed, spatially segregating the habitat. Territories frequently include Arundo stands but there is always a native component of the territory. Territories are roughly drawn- it would be interesting to see if territory size is larger when Arundo is present. Status/Distribution or Historic and Current Range: Historically the vireo was described as common to abundant in the appropriate riparian habitat from as far north as Tehama County, CA to northern Baja, Mexico. Habitat loss has fragmented most remaining populations into small, disjunct, widely dispersed subpopulations. Currently the largest population of vireos is on Marine Corps Base Camp Pendleton in San Diego County. This population combined the population in the Prado Basin represent approximately 60 % of all known territories in California. Arundo impacts: Arundo is abundant on the three largest population centers for the vireo: Santa Margarita, Santa Ana, and San Luis Rey. Vireos are in greater abundance on larger systems, but they do occur on smaller watersheds if riparian vegetation is well developed (Appendix B). Vireos also occur in greater abundance in urban riparian areas then other federally listed species. Decline and Threats: Decline of vireos is primarily the result of habitat loss and degradation, and cowbird nest-parasitism. The historic loss of wetlands (including riparian woodlands) has been estimated at 91 %. Much of the potential remaining habitat is infested with non-native plants and cowbirds. Ongoing causes of destruction or degradation of habitat include: removal of riparian vegetation; invasion of non-native species (e.g. Arundo, cowbird); thinning of riparian growth, especially near ground level; removal or destruction of adjacent upland habitats used for foraging; increases in human-associated or human induced disturbances; and flood control activities, including dams, channelization, water impoundment or extraction, and water diversion. Vireos are also sensitive to many forms of human disturbance, including noise, night lighting, and consistent human presence in an area. Overall impact metric for Arundo on least Bell’s vireo: Severe impact, score of 9. Interaction of Arundo distribution and least Bell’s vireo occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Stillwater Sciences. 2007. Focal Species Analysis and Habitat Characterization for the Lower Santa Clara River and Major Tributaries, Ventura County, California. Santa Clara River Parkway Floodplain Restoration Feasibility Study. Programmatic Biological Opinion for the Salinas River Watershed Permit Coordination Program, Monterey County, CA (1-8-02-F-19), US Fish and Wildlife Service, Ventura, CA. 2002. 7.2.13 Tidewater Goby (Eucyclogobius newberryi) Federal status: Endangered, March 7 1994. Critical habitat designated November 20 2000. State status: none Arundo impact score: 7 General Ecological Needs/Habitat Affinities: The tidewater goby, a species endemic to California, is found primarily in waters of coastal lagoons, estuaries, and marshes. The species is benthicin nature, and its habitat is characterized by brackish, shallow lagoons and lower stream reaches where the water is fairly still but not stagnant. Tidewater gobies prefer a sandy substrate for breeding, but they can be found on rocky, mud, and silt substrates as well. The species is typically found in water less than 1 m deep. Tidewater gobies have been documented in waters with salinitylevels from 0 - 42 parts per thousand (ppt), temperature levels from 8 - 25 ° C (46 - 77° F), and water depths from 25 200 cm (10 to 79 in). Critical habitat includes the stream channels and their associated wetlands, flood plains, and estuaries. Arundo impacts : Alteration of geomorphology and accumulation of excessive dead biomass in habitat areas are the primary impacts. It is possible that abundant Arundo is extremely detrimental to the species as they have not been observed on the Salinas River, Santa Clara, and Santa Margarita, and San Luis Rey Rivers in recent time frames. River channels could be becoming too deep for the species on some systems (such as San Luis Rey) resulting from excessive vegetation on floodplains (see chapter 5). The species now seems to occur on smaller river/creek systems, many of which have no or little Arundo on them (areas of Camp Pendleton and Estero Bay). Breeding/Life History: The tidewater goby is typically an annual species, although some variation has been observed. Reproduction occurs year-round although distinct peaks in spawning, often in early spring and late summer, do occur. Male tidewater gobies begin digging breeding burrows in relatively unconsolidated, clean, coarse sand (averaging 0.5 mm diameter), in April or May after lagoons close to the ocean. Female tidewater gobies can lay 300 - 500 eggs per clutch, and can lay 6 - 12 clutches per year. Male tidewater gobies remain in the burrow to guard the eggs that are attached to sand grains in the burrow ceiling and walls. The male tidewater goby cares for the embryos for approximately 9 - 11 days until they hatch. Tidewater goby larvae are planktonic for 1 - 3 days and then become benthic from that point on. Tidewater goby are preyed upon by native and non-native fish, and by fish eating birds. Arundo impacts: Accumulated biomass within the channel near the river mouth would cover substrate needed for reproduction. Diet: Tidewater gobies feed mainly on small animals, usually mysid shrimp, amphipods, ostracods, and aquatic insects. Juvenile tidewater gobies are generally day feeders, although adults mainly feed at night. Arundo impacts: Unknown if biomass would impacts aquatic food resources. Excessive channel depth would negatively affect feeding (individuals prefer a water depth of up to 1 m). Movement: The tidewater goby appears to spend all life stages in lagoons, estuaries, and river mouths. Tidewater gobies may enter marine environments only when flushed out of lagoons, estuaries, and river mouths by normal breaching of the sandbars following storm events. Tidewater gobies generally select habitat in the upper estuary, usually within the fresh-saltwater interface. Tidewater gobies range upstream a short distance (up to 1.5 miles/2.41 km) into fresh water, and downstream into water of up to about 75 % sea water (28 ppt). Arundo impacts this by: The preferred habitat zone frequently has significant Arundo on the banks (in highly invaded systems) It is possible that Arundo debris in these systems interferes with movement during and after flood events- particularly if there are large rafts vegetation (Arundo canes and native vegetation). Status/Distribution or Historic and Current Range: Tidewater gobies are endemicto California and historically ranged from Tillas Slough near the Oregon border to Agua Hedionda Lagoon in northern San Diego County, and are found today entirely within the original known range of the species. The known localities are discrete lagoons, estuaries, or stream mouths separated by mostly marine conditions. Tidewater gobies are absent from areas where the coastline is steep and streams do not form lagoons or estuaries. Tidewater gobies have recolonized areas where they have been extirpated. Arundo impacts: Arundo and goby distributions are shown Appendix B. As noted, the species has not been found in several large and heavily invaded watersheds since 2001. But there are smaller watersheds with populations nearby. Goby populations and distribution may naturally fluctuate in response to large flooding events. It will be informative to see if they return to systems that have had Arundo neatly eradicated (Santa Margarita and San Luis Rey). Decline and Threats: The tidewater goby is threatened by modification and loss of habitat as a result of coastal development, channelization of habitat, diversions of water flows, groundwater overdrafting, and alteration of water flows. Potential threats to the tidewater goby include discharge of agricultural and sewage effluents, increased sedimentation due to cattle grazing and feral pig activity, summer breaching of lagoons, upstream alteration of sediment flows into the lagoon areas, introduction of exoticgobies and rainwater killifish, habitat damage, and watercourse contamination resulting from vehicular activity in the vicinity of lagoons. Arundo impacts: Arundo effects several of these parameters (water availability, sediment transport), but it is unclear exactly how these factors interact with goby habitat. Overall impact metric for Arundo on the tidewater goby: High impact, score of 7. Interaction of Arundo distribution and tidewater goby occurrence is presented by watershed in Table 7-3 and Appendix B. It is important to note that there are many smaller watersheds that have no or very low Arundo presence and therefore impacts are non-existent. Goby have occurred on large systems- and they are in significant decline or do not occur on these systems over the time period when Arundo has become a significant impact. Other hydrologic factors have also changed significantly over that time frame (water flows, sediment transport, etc.) so several factors may be at play. Sources: Programmatic Biological Opinion for the Salinas River Watershed Permit Coordination Program, Monterey County, CA (1-8-02-F-19), US Fish and Wildlife Service, Ventura, CA. 2002. U.S. Fish and Wildlife Service. 2005. Recovery Plan for the Tidewater Goby (Eucyclogobius newberryi). U.S. Fish and Wildlife Service, Portland, Oregon. 7.2.14 Unarmored Three Spine Stickleback (Gasterosteus aculeatus williamsoni) Federal status: Endangered, October 13 1970. Designation of critical habitat remains pending. Recovery Plan completed in 1985. State status: Endangered, June 27 1971. Arundo impact score: 8 General Ecological Needs/Habitat Affinities: The unarmored three-spine stickleback inhabits slow moving reaches or quiet water microhabitats of streams and rivers. Favorable habitats usually are shaded by dense and abundant vegetation, but in more open reaches algal mats or barriers may provide refuge. The best habitat seems to be a small clean pond in the stream with a constant flow of water through it. Adults are found in all areas of the stream and tend to gather in areas of slower moving or standing water. In areas where water is moving rapidly, adults tend to be found behind obstructions, or at the edge of the stream, particularly under the edge of algal mats. No adults have been found to be living permanently in ponds isolated from the main stream. Arundo impacts: Arundo occurs within the core stickleback population area of the upper Santa Clara Watershed. There is Arundo present within much of the stickleback’s range and significant Arundo in the fish’s lower range on the main stem of the river. For more invaded portions of the river changes to sediment transport and high water use of Arundo could be impacting pool persistence and quality. Arundo fires in more invaded habitat would also cause impacts. Breeding/Life History: There is some reproduction during almost every month. A large increase in reproductive activity occurs in the spring in about March, and continues at lower levels throughout summer and fall. Males build nests of aquatic vegetation on the bottom within his territory. Nests are located where there is ample vegetation and a gentle flow of water. After the female lays the eggs, the male fertilizes them, guards them, and fans them. Young sticklebacks hatch in a nest from eggs which have been brooded for several days by the adult male. The exact amount of time the young stay in the nest is unknown. Larger juveniles and sub-adults tend to be found in the protection of vegetation, in slow moving or standing water. Fish apparently only live for one year. Arundo impacts: Pool/channel water quality and duration may be impacted. Diet: The stickleback feeds mostly on benthic insects, small crustaceans, and snails, and to a lesser degree flat worms and nematodes. Males may also eat stickleback eggs. Arundo impacts: Pool/channel water quality and duration may be impacted- which could effect abundance and diversity of food resources. Movement: The unarmored three-spine stickleback remains within stream channels and ponds within the stream area. No adults have been found to be living permanently in ponds isolated from the main stream. Arundo impacts: Minimal impacts. Status/Distribution or Historic and Current Range: Historically they were distributed throughout southern California, but are now restricted to the upper Santa Clara River and its tributaries in northern Los Angeles and Ventura Counties, San Antonio and Canada Honda creeks on Vandenberg Air Force Base in Santa Barbara County, and San Felipe Creek in San Diego County. The Canada Honda and San Felipe Creek populations were transplanted. Arundo impacts: Arundo and stickleback overlap in distribution (Appendix B). Decline and Threats: Habitat degradation from flood control and channelization are the primary threats to the unarmored three-spine stickleback. Habitat degradation also occurs from trampling of stream banks by humans and livestock, causing increased soil erosion and sedimentation which reduces availability of plants and insects for habitat and food. Damage to emergent vegetation along stream banks degrades the nursery areas. Stream channelization allows increased water velocity in pools, eliminates shallow backwaters and reduces aquatic vegetation. Channelization also increases peak flows during floods, and large flood events scour the channel and wash stickleback individuals downstream. Urbanization has caused a degradation of water quality due to increased run-off, siltation, nutrients, pesticides and other pollutants. These pollutants affect the health of the sticklebacks and can cause deformities. Introduced predators and competitors negatively affect the stickleback by directly removing individuals or restricting them to habitats that predators cannot enter. Other threats to the stickleback include genetic introgression, agricultural impacts, oxygen reduction, groundwater removal, possibly water loss due to transpiration from increase plant growth, and off-road vehicle use. Arundo impacts: Arundo stands on floodplains can create many of the same hydrologic and flow conditions as man-made channelization such as faster flows, high erosion within channels, etc. These factors may contribute to the sticklebacks decline by decreasing the elevation and channel complexity that stickleback may prefer over a simple deeper channel form. These factors are more relevant in the lower portions of the sticklebacks' range on the Santa Clara. Overall impact metric for Arundo on unarmored three-spine stickleback: Very high, score of 8. Interaction of Arundo distribution and unarmored three-spine stickleback occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Unarmored Threespine Stickleback Recovery Plan (Revised), U.S. Fish and Wildlife Service, Portland, Oregon, 1985. Biological and Conference Opinions for Annual Removal of Giant Reed and Tamarisk in Upper Santa Clara River Watershed, Los Angeles county, CA (File No. 2004-01540-AOA)(1-8-06-F-5). 7.2.15 Southern Steelhead (Oncorhynchus mykiss) Southern California Distinct Population Segment (DPS) Federal status: Endangered August 18 1997. Critical habitat was designated on September 2 2005. South-Central California Coast DPS Threatened Jan 5 2006, Critical habitat designated September 9 2005. Arundo impact score: 7 General Ecological Needs/Habitat Affinities: Southern steelhead can survive a wide range of temperature conditions, but require streams with adequate dissolved oxygen. Adult steelhead migrate from the ocean to freshwater spawning grounds. Spawning habitat consists of gravel substrates free of excessive silt. Adults do not feed during their upstream journey, rather use their energy reserves. Once they are large enough, smolts migrate downstream to the ocean, and to successfully complete this journey they require refuge areas with good cover and water quality. Riparian vegetation provides cover and protection from predators and areas of refuge from high velocities. Riparian vegetation is also important in maintaining low stream temperature, stabilizing banks, and providing food sources for migrating steelhead. To provide these benefits, riparian vegetation needs high vigor, density, and species diversity, including a mixture of canopy trees, brush and grasses. Areas of lowered velocity or reverse flow areas within the channel allow steelhead to use energy reserves efficiently during migration in order to save energy for spawning. Sediment removal of sandbars reduces flow-field complexity, particularly of edgewater eddies and low velocity zones. This likely results in adult steelhead migrating through higher velocities and consuming higher levels of reserved energy. If too much reserved energy is consumed, and sufficient resting pools are not available, adults could be unable to reach spawning grounds, or have less energy for reproductive development. Furthermore, modification of sandbars and velocities could also simply increase the amount of time it takes for steelhead to reach spawning grounds. Removing and/or altering sandbars also reduces the convergence of flows through pools, thus reducing the processes that maintain pools. Pools provide cover and refuge. During the upstream migration steelhead rest in pools and during downstream migration smolts take refuge in pools during the day. Adults and smolts both require adequate flows for migration; they need enough water flow to travel up and down the river/stream, and to keep the river mouth open to the ocean. Steelhead metabolism can be impacted by high water temperatures and the associated reduction in dissolved oxygen. Temperatures above 20° C have been known to stop fish migration, and temperatures above 25° C can be lethal to salmon and trout. High levels of suspended sediment (e.g. 3,000-4,000 mg/L), generally the result of large storm events or channel grading activities, can significantly impact fish migration and survival. Fish can suffer from gill abrasion and reduced visibility, and suffer mortality after exposure of two or more days. Fish at the mouth of a river would be delayed 1-2 days until the initial flush of sediment passes after a storm. Arundo impacts: Arundo has a significant number of impacts on river systems- some of which are negative and others that may be positive. Arundo typically occurs in areas that steelhead pass through so impacts to migration are important to explore. Arundo is not good at stabilizing eroding banks stands and clumps break off and are undercut by flows. This may increase erosion rates locally. Arundo does form dense stands of vegetation on floodplains. These dense stands create conditions that deepen low flow channels and push systems to single thread form in comparison to more complex braided systems or broader shallow systems. This single deep channel may aid migration of steelhead. However, single thread narrow channels have higher velocity and fewer areas to rest; this could be a detriment. Single thread channels also tend to transport (carry) greater suspended loads under a larger range of flow events. This could also be a detriment to steelhead, particularly if there a large number of sediment inputs (such as agricultural inputs or other disturbed sites). Highly invaded systems may have Arundo water use that reduces duration of surface flows- this would be a severe impact to steelhead. Water use may be lower at the time of year when fish migration occurs, partially offsetting transpiration rates. Arundo biomass could be a significant stressor as both a physical hindrance to passage and as a contamination in the water column. Water temperature impacts for portions of the habitat where fish passage is occurring are extremely difficult to quantify. It is not clear that large systems would have significant shading of the channel from mature gallery trees. Arundo shades a narrow band of the bank if the low flow channel is directly adjacent to the bank. More complex, but probably more relevant is water depth which may be strongly affected by Arundo stands (by effecting channel depth- chapter 5). Shading would be more relevant in upper portions of the watersheds where fish develop; these areas do not typically have Arundo in them. Breeding/Life History: Adult steelhead migrate from the ocean into freshwater streams to spawn between December and April. Female steelhead dig a nest in a stream area with suitable gravel composition, water depth, and velocity. Females may deposit eggs in four to five nests. Steelhead eggs hatch three to four weeks after being deposited. Juvenile steelhead typically spend one to two years rearing in freshwater before migrating to estuarine areas as smolts and then into the ocean to feed and mature. The majority of smolts enter the ocean at age two in March and April. They migrate at night and seek refuge and feed during the day. Steelhead can then remain at sea for up to three years before returning to fresh water to spawn. Arundo impacts: Arundo impacts on migration have been reviewed. Arundo debris in estuaries and Arundo effects on sediment movement could degrade estuarine habitat where smolts reside prior to entering the ocean. Diet: Young steelhead fry feed mostly on zooplankton. Adult steelhead eat aquatic and terrestrial insects, mollusks, crustaceans, fish eggs, minnows, and other small fishes. Arundo impacts: Little impact as Arundo is not typically present or abundant in the upper portions of watersheds where juveniles develop. There could be greater impacts on Ventura River, Estero Bay and Santa Ynez, but spawning grounds are not clearly indicated on data sets. Status/Distribution or Historic and Current Range: Steelhead within the Southern California DPS includes all naturally spawned anadromous steelhead populations below natural and manmade impassable barriers in streams from the Santa Maria River, San Luis Obispo County, California, to the U.S.-Mexico Border. South-Central California Coast DPS includes all naturally spawned anadromous steelhead from the Pajaro River (inclusive) to, but not including, the Santa Maria River, California. An estimated 30,000 - 50,000 steelhead once spawned in southern California rivers, but the recent runs in four major river systems were made by fewer than 500 adults total. Steelhead could once be found in 46 watersheds in the region, but only remained in 17 - 20 drainages by 2002. Many of these creeks and rivers now sustain only the resident form of steelhead, rainbow trout. Anadromous steelhead currently occur in only four large river systems in southern California: the Santa Maria, Santa Ynez, Ventura, and Santa Clara rivers. But periodic sightings have occurred on San Mateo (San Juan HU) and the San Luis Rey River. Arundo impacts: Arundo occurs in abundance on several critical watersheds and may occur on portions of spawning areas on a subset (Appendix B). Decline and Threats: Decline is due to long-standing human induced factors such as lack of flows due to groundwater pumping, dams and water diversions, blocked access to historic spawning and rearing areas upstream of dams, and channel modification. Arundo impacts: Arundo has significant impacts on water use, channel form, and sediment transport. These are complex hydro geomorphic processes explored in chapter 5. Most impacts would appear to be strongly negative, others could facilitate migration. Overall impact metric for Arundo on the southern steelhead: High impact, score of 7. Interaction of Arundo distribution and southern steelhead occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Programmatic Biological Opinion for the United States Army, San Francisco District Corps of Engineers’ permit pursuant to 404 of the Clean Water Act for Monterey County Water Resources Agency regional General Permit for the Salinas River Channel Maintenance Program; National Marine Fisheries Service, Southwest Region, Long Beach CA. July 2003. 7.2.16 Santa Ana Sucker (Catostomus santaanae) Federal status: Endangered, April 12 2000. Critical habitat has not been designated. State status: Species of special concern. Arundo impact score: 6 General Ecological Needs/Habitat Affinities: The sucker is fairly general in its habitat requirements, occupying both low-gradient, lowland reaches, and high-gradient, mountain streams. The sucker seems to do best in small to medium streams with higher gradients, clear water, and coarse substrates, such as the east fork of the San Gabriel River. Flowing water is essential, but can vary from slight to swift. It is typically associated with gravel, cobble, and boulder substrates, although it is also found over sand and mud substrates. Arundo impacts: Arundo abiotic impacts are of particular concern for the sucker, particularly high water use and modification of geomorphology and sediment transport on the Santa Ana. Arundo is not abundant in the low channel areas where fish occur. The Los Angeles River is steeper in gradient and Arundo, though present, is not abundant enough to significantly impact water availability and fluvial processes. Breeding/Life History: They live three to four years, but reach sexual maturity in one year and have high fecundity. Spawning generally occurs from late March to early July, with the peak in May and June. Arundo impacts: Probably low impact- but water use and drying of pools/stream sections could be a factor in some portions of the Santa Ana. Diet: The sucker feeds mostly on algae, diatoms, and detritus scraped form rocks and other hard substrate. Aquatic insects comprise only a small part of their diet. Arundo impacts: Probably low impact- but water use and drying of pools/stream sections could be a factor in some portions of the Santa Ana. Movement: Little is known about sucker movements, however other species in the same family are known to be high vagile and undertake spawning migrations. Arundo impacts: Probably low impact- but water use and drying of pools/stream sections could be a factor in some portions of the Santa Ana. Modification of sediment transport and fluvial processes would also affect channel forms and movement. Status/Distribution or Historic and Current Range: Historically the sucker occupied the Los Angeles, San Gabriel, and Santa Ana Rivers from near the Pacific Ocean to their uplands. It was described as common in the 1970s, but has since experienced declines throughout most of its range, and now persists in isolated, remnant populations. Approximately 70-80% of its historic range in the Los Angeles, San Gabriel and Santa Ana Rivers has been destroyed. Currently the sucker is found 1) in portions of Big Tujunga Creek between the Big Tujunga and Hansen dams along the Los Angeles River, 2) in the west, east and north forks of the San Gabriel River above Morris Dam, and 3) reaches of the Santa Ana River between the city of San Bernardino and the vicinity of Anaheim. There is also a population of suckers in the Santa Clara River that is thought to be introduced and that has hybridized with the Owen’s sucker, so it is not included within the range of the native sucker. Arundo impacts: Arundo significantly overlaps with the Santa Ana population and to a lesser degree the Los Angeles River population (Appendix B). There is also a hybridized population on the Santa Clara that may be introduced. There is significant Arundo within this populations range. The Santa Clara watershed is given a distribution score (Appendix B) but it is lowered to reflect the questionable genetic integrity of the resident population. If revisions to the Santa Clara's population value are made a higher impact interaction score should be given. Decline and Threats: Threats that have contributed to the decrease in the sucker include 1) destruction and degradation of habitat through urbanization, channelization, flood control structures, water diversion, water withdrawal, and water quality reduction, 2) direct loss of suckers due to water diversion, 3) competition and predation from non-native species, and 4) loss of connectivity. Overall impact metric for Arundo on the Santa Ana sucker: Moderate/High, score of 6. Interaction of Arundo distribution and Santa Ana sucker occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Biological Opinion on the Prado Mainstem and Santa Ana River Reach 9 Flood Control Projects and Norco Bluffs Stabilization Project, Orange, Riverside, and San Bernardino Counties, California; U.S> Fish and Wildlife Service, Carlsbad, CA, December 2005. 7.2.17 San Joaquin Kit Fox (Vulpes macrotis mutica) Federal status: Endangered, March 11, 1967. No critical habitat has been designated. State status: Threatened, June 27, 1971. Arundo impact score: 1 General Ecological Needs/Habitat Affinities: This species historically inhabited grassland, scrubland, and wetland communities in the San Joaquin Valley and adjacent habitat. Today kit foxes are found in grassland and scrubland communities, most of which have been extensively modified by humans. Kit foxes use dens for temperature regulation, shelter from adverse weather and protection from predators. They either dig their own dens, use those constructed by other animals, or use human-made structures (culverts, abandoned pipelines, or banks in sumps or roadbeds). Kit foxes often change dens and many dens may be used throughout the year. The majority of their dens lie in relatively flat terrain or gently sloping hills, in washes, drainages, and roadside berms. Arundo impacts: Arundo is not abundant within the habitat occupied by foxes. However, it does degrade the habitat as foxes prefer very open habitat with little or no vegetation structure to avoid predation. Arundo creates structure and may interact with dens that occur on washes. Breeding/Life History: Kit foxes can breed when one year old. Adult pairs stay together all year. During September and October, females begin to clean and enlarge their pupping dens. Mating occurs between December and March. Litters of two to six pups are born in February or March. Pups emerge from the den after about a month. Arundo impacts: Very minor impacts related to potentially higher predation and lower denning quality. Diet: Kit fox eat small mammals such as mice, kangaroo rats, squirrels and rabbits. They also eat ground- nesting birds and insects. They are primarily nocturnal hunters. Arundo impacts: No impact likely. Movement: The kit fox is mostly nocturnal, but can be active in the daytime during cool weather. Home ranges of approximately one to twelve square miles have been reported. Development has significantly degraded movement and dispersal corridors for young kit foxes. Juvenile survival and successful dispersal has been declining in recent years. Three occurrences of kit fox movement have been documented between the Salinas-Pajaro region and the Carrizo Plain Natural Area. Although the total movement of kit foxes between these areas is unknown, land development along the natural movement corridors between Carrizo Plain and the Salinas Valley, as well as development within Salinas Valley has probably reduced immigration of kit foxes into the Salinas Valley, possibly contributing to their decline. Arundo impacts: Dense Arundo stands may inhibit movement to new areas as kit foxes prefer open areas. Riparian corridors are extremely important for movement of wildlife. Foxes may use roads as alternate corridors if riparian zones are overly vegetated (Arundo), leading to increased mortality from vehicles. Arundo is not abundant enough on the upper Salinas to significantly discourage use of riparian habitat as a corridor- but migration and use of riparian habitat downstream (north) in Salinas valley could be reduced by Arundo, particularly below King City where Arundo cover is very high. Status/Distribution or Historic and Current Range: In the San Joaquin Valley before 1930, the range of the San Joaquin kit fox is believed to have extended from southern Kern County north to Contra Costa County on the west side and near La Grange, Stanislaus County, on the east side. Until the 1990s, Tracy was the farthest northwest record, but now there are records from the Antioch area of Contra Costa County. By 1930, the kit fox range had been reduced by more than half, with the largest portion remaining in the southern and western parts of the Valley. By 1958, an estimated 50% of the Valley's original natural communities had been lost, due to extensive land conversions, intensive land uses, and the use of pesticides. In 1979, only about 6.7% of the San Joaquin Valley's original wildlands south of Stanislaus County remained untilled and undeveloped. Today many of these communities are represented only by small, degraded remnants. Kit foxes are, however, found in grassland and scrubland communities, which have been extensively modified by humans with oil exploration, wind turbines, agricultural practices and/or grazing. The kit fox population is fragmented, particularly in the northern part of the range. Arundo impacts: Arundo and foxes co-occur in the Salinas watershed (Appendix B). Decline and Threats: Kit foxes are subject to competitive exclusion or predation by other species, such as the nonnative red fox, coyote, domestic dog, bobcat, and large raptors. Loss and degradation of habitat by agricultural, industrial, and urban developments and associated practices continue, decreasing the carrying capacity of remaining habitat and threatening kit fox survival. Such losses contribute to kit fox declines through displacement, direct and indirect mortalities, barriers to movement, and reduction of prey populations. Overall impact metric for Arundo on the San Joaquin kit fox: Extremely low/improbable, score of 1. If high quality habitat was identified north of Salinas range where Salinas River could serve as a corridor, then Impact score should be increased. Interaction of Arundo distribution and the San Joaquin kit fox occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Programmatic Biological Opinion for the United States Army, San Francisco District Corps of Engineers’ permit pursuant to 404 of the Clean Water Act for Monterey County Water Resources Agency regional General Permit for the Salinas River Channel Maintenance Program; National Marine Fisheries Service, Southwest Region, Long Beach CA. July 2003. Species Account SAN JOAQUIN KIT FOX (Vulpes macrotis mutica), U.S. Fish & Wildlife Service, Sacramento Fish & Wildlife Office. 7.2.18 San Diego Ambrosia (Ambrosia pumila) Federal status: Endangered, July 2 2002. Final critical habitat designated November 30 2010. State status: None? Arundo impact score: 7 General Ecological Needs/Habitat Affinities: Ambrosia pumila is a perennial herb in the sunflower family (Asteraceae). It occurs primarily on upper terraces of rivers and drainages. Within these areas, the species is found in open grassland of native and nonnative plant species, and openings in coastal sage scrub, and primarily on sandy loam or clay soils. The species may also be found in ruderal habitat types (disturbed communities containing a mixture of native and non-native grasses and forbs) such as fire fuel breaks and edges of dirt roadways. Non-native grassland and ruderal habitat types provide adequate habitat for A. pumila; however, non-native plants can out-compete A. pumila plants for resources in some situations. Ambrosia pumila consistently occurs in areas near waterways such as upper terraces of rivers or other water bodies. These areas do not necessarily provide high levels of soil moisture, and A. pumila is adapted to dry conditions. A. pumila may require periodic flooding for some segment of its life cycle. Additionally, areas subject to periodic flooding may be less amenable to competing non-native and native plants. A. pumila is a clonal herbaceous perennial plant that spreads vegetatively by means of slender, branched, underground root like rhizomes from which new aboveground stems (aerial stems or ramets) arise each year. Aerial stems of Ambrosia pumila sprout from their underground rhizomes in early spring after winter rains, and flower between May and October. However, aerial stems have been observed sprouting under dry conditions in late fall. The aerial stems senesce after the growing season, leaving the rhizome system in place from which new aerial stems may sprout when environmental conditions are appropriate. Little is known about its reproductive system, but it is presumed to be wind-pollinated. It is thought to have limited sexual reproductive output due to low production of viable seed. The dispersal strategy of A. pumila is unknown and the seeds lack structures that facilitate dispersal by wind or passing animals. It may depend on periodic flooding of nearby waterways for dispersal of seeds and rhizomes that can produce new aerial stems. The longevity of individual plants and of seeds, and the potential for buried seed banks to develop in the soil are unknown. Arundo impacts: Arundo and A. pumila overlap in range and in habitat. This creates the potential for direct competition and for impacts related to water use, fire and modification of geomorphic processes. These are slightly mitigated by the fact that ambrosia is present in the higher elevation portions of the riparian zone- higher terraces and transition/eco-tones with scrub and grass lands. Arundo debris may cover plants habitat. Arundo fires may result in take and or type conversion. Modified flood and sediment transport may decrease habitat fitness and interfere with seed dispersal of ambrosia. Status/Distribution or Historic and Current Range: Ambrosia pumila is distributed in southern California from northwestern Riverside County, south through western San Diego County, to northwestern Estado de Baja California, Mexico. It is generally found at or below elevations of 487 m (1,600 ft) in Riverside County, and 183 m (600 ft) in San Diego County. At the time of listing, 15 native occurrences of A. pumila were considered extant in the United States: 3 in Riverside County and 12 in San Diego County (native is used here to differentiate these from occurrences derived from plants translocated to another site). Arundo impacts: Ambrosia is present on highly invaded watersheds, specifically San Diego and San Luis Rey (Appendix B). The strong overlap in range makes larger scale impacts to ambrosia relevant. On Santa Ana one population near Lake Elsinore appears to above the river and little Arundo is present up stream or nearby. The other Santa Ana population is historic (1940), but is near large Arundo infestations on the main river. If new populations were found there could be greater potential for impacts on Santa Ana. Decline and Threats: Loss and degradation of Ambrosia pumila habitat is the result of development, non-native plants, fuel modification, altered hydrology and fragmentation. Development results in direct loss of habitat. Competition from non-native plants, primarily non-native grasses and forbs, pose a significant threat to the species throughout its range. No research has been done to clarify the specific effects of non-native plants on Ambrosia pumila, but a recent study by the Center for Natural Lands Management in San Diego County demonstrated that reduction of non-natives increased percent cover of Ambrosia pumila. Fuel modification activities that can negatively affect Ambrosia pumila include weed abatement, fire suppression, and landscaping practices (including mowing, discing, and plowing). Altered hydrology has the potential to impact Ambrosia pumila. It almost always occurs on the upper terraces of rivers/streams or near the margins of vernal pools, where under natural conditions the plants would likely be subjected to inundation during large-scale flooding events. If Ambrosia pumila is dependent on these periodic flooding events for some aspect of its life history (e.g., seed germination, dispersal) or control of competing plants, altering the flooding regimes of associated waterways or vernal pools could have a significant impact on the species. However, it is unknown if and to what degree Ambrosia pumila is dependent upon periodic flooding or other aspects of its proximity to waterways. Overall impact metric for Arundo on the San Diego ambrosia: High impact, score of 7. Interaction of Arundo distribution and San Diego ambrosia occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Ambrosia pumila (San Diego ambrosia) 5 Year Review and Summary, US Fish and Wildlife Service, Carlsbad Office, CA, July 15 2010. http://ecos.fws.gov/docs/five_year_review/doc3557.pdf 7.2.19 Marsh Sandwort (Arenaria paludicola) Federal status: Endangered, August 3, 1993. Critical habitat has not been designated. State status: Endangered, February 1990. Arundo impact score: 4 General Ecological Needs/Habitat Affinities: Marsh sandwort is an herbaceous green perennial in the Caryophyllaceae family that is often supported by surrounding vegetation. The trailing stems often root at the nodes and can be up to 1 m long. The opposite leaves are lanceolate and narrowly sharp pointed with a solitary mid-vein. It blooms from May to August. Flowers are small, white and borne singly on long stalks. Marsh sandwort is found in freshwater marshes from elevations to about 1,476 ft (450 m) with saturated soils and acidic bog soils, predominantly sandy with high organic content. Vegetation around the Black Lake Canyon population includes emergent freshwater marsh species and some riparian woodland or wetland tree species, mainly willow and wax myrtle. The two existing populations of marsh sandwort in San Luis Obispo County are found in freshwater marshes located within a system of active to partly-stabilized sand dunes. Arundo impacts: Minor impacts on the upper Santa Ana to a very old historic sighting (1899). Status/Distribution or Historic and Current Range: Historically it has been collected by botanists from scattered locations near the Pacific coast in southern and central California and Washington. Only two of California’s seven historical populations are known to exist today, near the southern San Luis Obispo County coast at Black Lake Canyon on Nipomo Mesa and at Oso Flaco Lake further south. Arundo impacts: Only one historic signing on Santa Ana River (Appendix B). Decline and Threats: Immediate threats to the survival of marsh sandwort include habitat destruction, habitat degradation, and competition with non-native species for light, nutrients and space. Arundo impacts: Arundo would be a stressor and competitor if it were re-discovered on the Santa Ana River. Overall impact metric for Arundo on the marsh sandwort: Low/moderate impact, score of 4. Interaction of Arundo distribution and marsh sandwort occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Recovery Plant for marsh sandwort (Arenaria paludicola) and Gambel’s watercress (Rorippa gambelii). U.S. Fish and Wildlife Service, Portland, Oregon, 1998. 7.2.20 San Jacinto Valley Crownscale (Atriplex coronata var. notatior) Federal status: Endangered, October 1998. Critical habitat has not been designated. State status: none Arundo impact score: 7 General Ecological Needs/Habitat Affinities: San Jacinto Valley crownscale is an annual plant in the goosefoot family (Chenopodiaceae). It grows 4 to 12 inches (30.5 cm) tall with grayish colored leaves. The plant generally flowers in April and May. This bushy plant can have one or several gray-green stems, which turn deep yellow as it grows older and dies. San Jacinto Valley crownscale is restricted to highly alkaline and silty-clay soils. These soils are found in certain alkali sink scrub, alkali playa, vernal pool, and annual alkali grassland habitats. Habitat for San Jacinto Valley crownscale is typically flooded during winter rains and the plant emerges as waters recede in the spring. Arundo impacts: Crownscale does occur in wash areas/floodplain on Alberhill Creek north of Lake Elsinore, where significant Arundo stands also occur. Therefore the two species interact and compete with each other for resources and space. Status/Distribution or Historic and Current Range: San Jacinto Valley crownscale has a narrow range of distribution and is only known to occur in western Riverside County. Within western Riverside County, there are four general population centers of the plant – in the floodplain of the San Jacinto River at the San Jacinto Wildlife Area/Mystic Lake; in the San Jacinto River floodplain between the Ramona Expressway and Railroad Canyon Reservoir; in the Upper Salt Creek Vernal Pool Complex in the west Hemet area; and in the floodplain of Alberhill Creek north of Lake Elsinore. The San Jacinto Valley crownscale experienced a severe decline between 1992 and 1999, when it lost 70 % of its population; it continues to decline today. Because floodwaters carry crownscale seeds over long distances, population ranges may shift from year to year. Arundo impacts: As shown in Appendix B Arundo and San Jacinto Valley crownscale overlap in range. Closer examination of polygon data shows clear co-occurrence within the riparian areas. Decline and Threats: The San Jacinto Valley crownscale is in particular danger from increased urbanization because its habitat is nearly flat and therefore easy to develop. It is also threatened by habitat fragmentation, agricultural weed-control measures where its habitat is repeatedly disked, off-road vehicle use, alteration of hydrology, deliberate manure and sludge dumping, trampling by livestock, and competition from nonnative species. Arundo impacts: The sites have all of these impacts: agricultural use, urban use, water management facilities. Arundo adds to the population’s stress by directly competing against it. Arundo is also dense enough to add biomass debris over crownscale habitat following flood events. Fire could also impact habitat and sedimentation. Of added concern is response to fire and flood events that are of greater magnitude due to high Arundo cover. The area has heavy infrastructure (roads, water transfer, levees, agriculture use, etc.) that would likely lead to damaging emergency actions in response to events. Overall impact metric for Arundo on the San Jacinto Valley crownscale: High Impact, score of 7. Interaction of Arundo distribution and San Jacinto Valley crownscale occurrence is presented by watershed in Table 7-3 and Appendix B. Sources: Species Profile for San Jacinto Valley crownscale (Atriplex coronata notatior), U.S. Fish and Wildlife Service, http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=Q2ZR 7.2.21 Nevin's Barberry (Berberis nevinii) Federal status: Endangered, October 13, 1998. Critical habitat designated on February 13 2008. State status: Endangered, January 1987. Arundo impact score: 4 General Ecological Needs/Habitat Affinities: Nevin’s barberry is a large rounded shrubby member of the barberry family (Berberidaceae) that grows up to 13 ft (4 m) tall, with blue-green, spiny pinnate leaves. It is widely cultivated and popular in xeric gardens, in part for its bright red edible berries and bright yellow flowers that bloom March through April. Nevin’s barberry generally grows within sandy, gravelly soil, on north facing slopes or low gradient washes. On north-facing slopes, it is associated with coastal scrub and chaparral habitat, while in low gradient washes it is found in alluvial and riparian scrub. In general, the plant occurs from 800- 5200 ft (1,585 m) above sea level, with local distribution potentially related to the presence of groundwater. Associated plant communities are alluvial scrub, riparian scrub or woodland, coastal sage scrub, chaparral, and/or oak woodland. Arundo impacts: Arundo occurs within population ranges of barberry when plants are located within low gradient washes. These are not usually areas where Arundo becomes overly abundant, but it be locally abundant. Direct competition between plants as sites could occur. Abiotic impacts are unlikely due to limited extent of Arundo upstream of washes where barberry occurs. Status/Distribution or Historic and Current Range: The distribution of Nevin’s barberry is scattered, with populations located throughout southern California in Los Angeles, Riverside, and San Bernardino counties. There have been a total of 34 occurrences of Berberis nevinii reported in southern California, five of which have been or are presumed extirpated and 7 considered to have been introduced. Total number of individuals is estimated at 500, with approximately half of those as naturally occurring individuals. In addition, the majority of occurrences are comprised of only one to few individuals, with little to no reproduction observed. Arundo impacts: Arundo and barberry co-occur in Santa Clara (Arundo is scattered to dense), and several area on the Los Angeles and San Gabriel Rivers (Arundo is scattered, Appendix B). Decline and Threats: Population decline is likely related to low fecundity and habitat loss. Populations that occur in alluvial washes are threatened by urban and agricultural development, competition by non-native plant species, off-road vehicle activity, road maintenance, and vegetation clearing and channelization for flood control. While population sizes vary considerably among extant groups, the majority of occurrences are comprised of only one to a few individuals, with little to no reproduction observed. Most of the historic habitat of Nevin’s barberry has been eliminated by agriculture, urban development, and flood control and stream channelization. Overall impact metric for Arundo on the Nevin’s barberry: Low/moderate impact, score of 4. Interaction of Arundo distribution and Nevin’s barberry occurrence is presented by watershed in Table 7-3 and distribution is shown in Appendix B. Sources: Stillwater Sciences. 2007. Focal Species Analysis and Habitat Characterization for the Lower Santa Clara River and Major Tributaries, Ventura County, California. Santa Clara River Parkway Floodplain Restoration Feasibility Study. Center for Plant Conservation, National Collection Plant Profile for Nevin’s Barberry, http://www.centerforplantconservation.org/collection/cpc_viewprofile.asp?CPCNum=2777 7.2.22 Spreading Navarretia (Navarretia fossalis) Federal status: Threatened, October 13 1998. Critical habitat: October 18 2005. A proposal for revised critical habitat was initiated on June 10 2009. State status: None Arundo impact score: 6 General Ecological Needs/Habitat Affinities: Spreading navarretia is an annual plant in the Polemoniaceae (phlox family). It is a low, mostly spreading or ascending plant 4 - 6 inches (10 - 15 cm ) tall. The leaves are long and finely divided into slender spine-tipped lobes and the lavender-white flowers are arranged in flat-topped, compact, leafy heads. Each seed is covered by a layer that becomes sticky and viscous when the capsule is moistened. Spreading navarretia is typically found in vernal pool (seasonal depression wetlands) habitat, particularly in Los Angeles and San Diego Counties. In western Riverside County, however, Navarettia fossalis is associated with seasonally flooded alkali vernal plain habitat that includes alkali playa (highly alkaline, poorly drained), alkali scrub, alkali vernal pool, and alkali annual grassland components. Navarretia fossalis depends on the inundation and drying cycles of its habitat for survival. It germinates from seeds left in the seed bank. Most Navarretia species have indehiscent fruit, or fruit with fibers that absorb water and expand to break open the fruit after a substantial rain. The timing of germination is important so that the plant germinates under favorable conditions in the spring rather than the summer, autumn, or winter. Navarretia fossalis abundance also varies from year to year depending on precipitation and the inundation/drying time of the vernal pool. The occurrences of plants can also vary spatially in alkali playa habitat where pools are not in the same place from year to year. After germination, the plant usually flowers in May and June as the vernal pool is devoid of water. The plant then produces fruit, dries out, and senesces in the hot, dry summer months. Arundo impacts: Although navarretia habitat sounds restrictive Arundo co-occurs with the Riverside San Jacinto Valley navarretia population (Appendix B). This area is a broad floodplain and is the same area where San Jacinto crownscale is found. This area has a narrow river thread heavily invaded with Arundo bordered by flat floodplains. Impacts described in the crownscale section ally to this species as well (risk of fire, Arundo debris, flood damage and 'emergency actions' to repair and protect infrastructure. Status/Distribution or Historic and Current Range: Spreading navarretia extends from northwestern Los Angeles County to western Riverside County, and coastal San Diego County in California, to San Quintin in northwestern Baja California, Mexico. Arundo impacts this by: As noted these species co-occur in San Jacinto Valley (Appendix B).Populations of navarretia that occur in San Diego County watersheds typically occur in vernal pools where Arundo is not present. The Santa Clara navarretia population also occurs in a vernal pool. Decline and Threats: Threats include agriculture, fragmentation, grazing and urbanization. Overall impact metric for Arundo on spreading navarretia: Moderate/high Impact, score of 6. Interaction of Arundo distribution and spreading navarretia occurrence is presented by watershed in Table 7-3. Sources: Center for Plant Conservation, National Collection Plant Profile for spreading navarretia, http://www.centerforplantconservation.org/collection/CPC_ViewProfile.asp?CPCNum=2930 5-Year Review for spreading navarretia (Navarretia fossalis) U.S. Fish and Wildlife Service, http://ecos.fws.gov/docs/five_year_review/doc2574.pdf Table 7-3. Examination of Arundo impacts on federally listed species by watershed. ‘Arundo impact rank’ and ‘overlap rank’ (potential for interaction between Arundo and listed species distribution and abundance) for each species. The cumulative impact score is in Table 7-4. Federal Arundo Category Scientific name Common name Listing1 Impact Arundo donax Distribution and Impact Report 192 anaujiT yrautsE yatO retaw-teewS /ogeiD.S sotiuqsaneP otiugeiD naS dabslraC yeR siuL naS atnaS atiragraM nauJ naS naS otiuqsicnarF tropweN /krC anA atnaS /.A.L /leirbaG naS acinoM atnaS sauguellaC aralC atnaS arutneV ,arabraB.S tsaoChtuoS zenY.S& yaB oretsE sanilaS /zurC.S otineB Count Ambystoma California tiger Amphibian En 1 - - - - - - - - - - - - - - - - - 3 3 2 californiense salamander2 Amphibian En Bufo californicus Arroyo toad 10 - - 5 3 7 - 10 10 7 7 - 3 - 4 - - - 2 - 10 California red- Amphibian Th Rana aurora draytonii 3 - - - - - - - - - - - - - - 8 2 5 2 3 5 legged frog Mountain yellow- Amphibian En Rana muscosa 4 - - - - - - - - - - 4 6 - - - - - - - 2 legged frog Charadrius Western snowy Bird Th 5 1 1 1 6 - 8 - 9 - - 0 4 0 1 - 1 - - - 9 alexandrinus nivosus plover Sp of Coccyzus americanus Western yellow- Bird 7 - - 1 - - - - 1 0 - 7 - - 4 - - 1 - - 5 Concern occidentalis billed cuckoo Empidonax traillii Southwestern Bird En 8 - - 2 2 3 2 10 10 3 - 6 1 - 2 - 2 - - - 11 extimus willow flycatcher Sp of Passerculus Belding's savannah Bird 2 3 3 3 3 3 3 - - - 2 2 2 6 - - 2 - - - 11 Concern sandwichensis beldingi sparrow Polioptila californica Coastal California Bird Th 2 3 3 3 3 3 3 4 4 3 4 4 2 2 1 - - - - - 14 californica gnatcatcher Rallus longirostris Light-footed Bird En 3 2 2 3 2 2 4 2 3 - 2 - - 1 - - 1 - - - 11 levipes clapper rail Sterna antillarum California least Bird En 4 - 1 - 3 2 4 - 7 - 1 - 1 - 1 - - - - - 8 browni tern Bird En Vireo bellii pusillus Least Bell's vireo 9 4 4 4 4 4 3 9 10 6 6 10 4 3 3 3 1 - - - 14 Fish En Eucyclogobius Tidewater goby 7 - - - - - 4 8a 8 a - - - - 3 6a 8 5 3 4 1 7 newberryi Gasterosteus aculeatus Unarmored three Fish En 8 - - - - - - - - - - - - - 8 - - - - - 1 williamsoni spine stickleback Fish En&Th3 Oncorhynchus mykiss Steelhead 7 - - - - - - 1 - 1 - - 4 - 8 8 7 5 8 5 9 Fish Th Catostomus santaanae Santa Ana sucker 6 - - - - - - - - - - 9 7 - 4 - - - - - 3 Mammal En Vulpes macrotis mutica San Joaquin kit fox 1 - - - - - - - - - - - - - - - - - 2 - 1 San Diego Plant En Ambrosia pumila 7 - 2 - - 7 - 7 - - - 2 - - - - - - - - 4 ambrosia Plant En Arenaria paludicola Marsh sandwort 4 - - - - - - - - - - 1 - - - - - - - - 1 Atriplex coronata var. San Jacinto Valley Plant En 7 - - - - - - - - - - 10 - - - - - - - - 0 notatior crownscale Plant En Berberis nevinii Nevin’s Barberry 4 - - - - - - - - - - - 5 - 3 - - - - - 2 Spreading Plant Th Navarretia fossalis 6 - - - - - - - - - - 10 - - 1 - - - - - 1 navarretia 1 En = Endangered, Th = Threatened, Sp of Concern = Species of Concern 2 Santa Barbara Distinct Population Segment (DPS) 3 Southern California (DPS) is endangered, South-Central California Coast DPS is threatened. a Recent historic 1990s/2000 Table 7-4. Cumulative impact scores for Arundo impacts on threatened and endangered species by watershed. The cumulative impact score is calculated by multiplying the Arundo impact rank by overlap rank. Impact scores are for each watershed and species, and are totaled for each watershed and species. Federal Category Scientific name Common name Listing1 anaujiT yrautsE yatO retaw-teewS /ogeiD.S sotiuqsaneP otiugeiD naS dabslraC yeR siuL naS atnaS atiragraM nauJ naS naS otiuqsicnarF tropweN /krC anA atnaS /.A.L /leirbaG naS acinoM atnaS sauguellaC aralC atnaS arutneV ,arabraB.S tsaoChtuoS zenY.S& yaB oretsE sanilaS /zurC.S otineB Total Ambystoma California tiger Amphibian En - - - - - - - - - - - - - - - - - 3 3 6 californiense salamander2 Amphibian En Bufo californicus Arroyo toad - - 50 30 70 - 100 100 70 70 - 30 - 40 - - - 20 - 580 California red- Amphibian Th Rana aurora draytonii - - - - - - - - - - - - - - 24 6 15 6 9 60 legged frog Mountain yellow- Amphibian En Rana muscosa - - - - - - - - - - 16 24 - - - - - - - 40 legged frog Charadrius Western snowy Bird Th 5 5 5 30 - 40 - 45 - - - 20 - 5 - 5 - - - 160 alexandrinus nivosus plover Sp of Coccyzus americanus Western yellow- Bird - - 7 - - - - 7 - - 49 - - 28 - - 7 - - 98 Concern occidentalis billed cuckoo Empidonax traillii Southwestern Bird En - - 16 16 24 16 80 80 24 - 48 8 - 16 - 16 - - - 344 extimus willow flycatcher Sp of Passerculus Belding's savannah Bird 6 6 6 6 6 6 - - - 4 4 4 12 - - 4 - - - 64 Concern sandwichensis beldingi sparrow Polioptila californica Coastal California Bird Th 6 6 6 6 6 6 8 8 6 8 8 4 4 2 - - - - - 84 californica gnatcatcher Rallus longirostris Light-footed Bird En 6 6 9 6 6 12 6 9 - 6 - - 3 - - 3 - - - 72 levipes clapper rail Sterna antillarum California least Bird En - 4 - 4 8 16 - 28 - 4 - 4 - 4 - - - - - 72 browni tern Bird En Vireo bellii pusillus Least Bell's vireo 36 36 36 36 36 27 81 90 54 54 90 36 27 27 27 9 - - - 702 Eucyclogobius Fish En Tidewater goby - - - - - - 56 56 - - - - 21 42 - 35 21 28 7 266 newberryi Gasterosteus aculeatus Unarmored three Fish En - - - - - - - - - - - - - 64 - - - - - 64 williamsoni spine stickleback Fish En&Th3 Oncorhynchus mykiss Steelhead - - - - - - 7 - 7 - - 28 - 56 56 49 35 56 35 329 Fish Th Catostomus santaanae Santa Ana sucker - - - - - - - - - - 54 42 - 24 - - - - - 120 Mammal En Vulpes macrotis mutica San Joaquin kit fox - - - - - - - - - - - - - - - - - 2 - 2 San Diego Plant En Ambrosia pumila 0 14 - - 49 - 49 - - - 14 - - - - - - - - 126 ambrosia Plant En Arenaria paludicola Marsh sandwort - - - - - - - - - - 4 - - - - - - - - 4 Atriplex coronata var. San Jacinto Valley Plant En - - - - - - - - - - 70 - - - - - - - - 70 notatior crownscale Plant En Berberis nevinii Nevin’s Barberry - - - - - - - - - - - 20 - 12 - - - - - 32 Spreading Plant Th Navarretia fossalis - - - - - - - - - - 60 - - 6 - - - - - 66 navarretia Total: 59 77 135 134 205 123 387 423 161 146 417 220 67 326 107 127 78 115 54 3,361 1 En = Endangered, Th = Threatened, Sp of Concern = Species of Concern 2 Santa Barbara Distinct Population Segment 3 Southern California Distinct Population Segment (DPS) is endangered, South-Central California coast DPS is threatened. Table 7-5. Cumulative Arundo impact score for each species for all watersheds combined, and sum and average for each taxa group. Cumulative Federal Impact Score Summary for Category Scientific name Common name Listing1 for all Taxa Group watersheds Ambystoma California tiger Amphibian En 6 californiense salamander2 Amphibian En Bufo californicus Arroyo toad 580 Sum – 686 California red-legged Ave – 171.5 Amphibian Th Rana aurora draytonii 60 frog Mountain yellow- Amphibian En Rana muscosa 40 legged frog Charadrius Western snowy Bird Th 160 alexandrinus nivosus plover Sp of Coccyzus americanus Western yellow- Bird 98 Concern occidentalis billed cuckoo Empidonax traillii Southwestern willow Bird En 344 extimus flycatcher Sp of Passerculus Belding's savannah Bird 64 Sum – 1,596 Concern sandwichensis beldingi sparrow Ave – 199.5 Polioptila californica Coastal California Bird Th 84 californica gnatcatcher Rallus longirostris Light-footed clapper Bird En 72 levipes rail Sterna antillarum Bird En California least tern 72 browni Bird En Vireo bellii pusillus Least Bell's vireo 702 Eucyclogobius Fish En Tidewater goby 266 newberryi Gasterosteus aculeatus Unarmored three Fish En 64 Sum – 779 williamsoni spine stickleback Ave – 194.8 Fish En&Th3 Oncorhynchus mykiss Steelhead 329 Fish Th Catostomus santaanae Santa Ana sucker 120 Mammal En Vulpes macrotis mutica San Joaquin kit fox 2 2 Plant En Ambrosia pumila San Diego ambrosia 126 Plant En Arenaria paludicola Marsh sandwort 4 Atriplex coronata var. San Jacinto Valley Sum – 298 Plant En 70 notatior crownscale Ave – 59.6 Plant En Berberis nevinii Nevin’s Barberry 32 Plant Th Navarretia fossalis Spreading navarretia 66 Total: 3,361 7.3 Results 7.3.1 Summary by Species and Group 7.3.1.1 Impact Scores Within the study area, 22 federally protected species were found to be impacted at some level by the presence of Arundo. The magnitude of the impact score ranged from 10 (very severe) to 1 (very low/improbable) (Table 7-3). Five taxonomic groups are represented: amphibian, avian, fish, mammal, and plant. All groups have a minimum of four species with the exception of mammal, which had one. Amphibians had the widest range of Arundo impact scores among the groups. Arroyo toads had severe impacts from Arundo, both abiotic and biotic. The other amphibian species (California tiger salamander, California red-legged frog, and mountain yellow-legged frog) were less impacted due to greater habitat use in foothills and mountains where Arundo is less abundant. In these areas, Arundo is less likely to directly impact the species or to generate enough biomass to degrade habitat significantly. Avian species fell into two general classes based on the habitat they use. Species that use riparian habitat had impact scores that ranged from high (7) to severe (9), reflecting both abiotic and biotic impacts. This included the least Bell’s vireo, southwestern willow flycatcher and yellow-billed cuckoo. Species that use estuary and beach areas were also impacted by Arundo, usually as a function of biomass accumulating in habitat areas (discharged from upstream riparian areas), but also to a lesser degree from Arundo growing in estuaries and on beaches. Avian species that use beach and estuary habitat had impact scores ranging from moderate (5) to very low (2), reflecting Arundo impacts on breeding and predation. In addition to these two classes, the gnatcatcher had a low impact score (2), because it does not breed or feed exclusively in riparian habitat. Avian species were also, as a group, susceptible to physical changes in habitat structure, encouraging predators that use Arundo as perches and/or dense cover for denning. Fish species had fairly uniform impacts from Arundo related to modification of abiotic processes that control geomorphology and hydrology. Modification of channel form and depth is a significant change to habitat structure. Arundo biomass and shading also have possible effects on habitat quality. Fish habitat varies depending on the species. It may occur only near the river mouth (tidewater goby), reside along river/stream corridors (Santa Ana sucker, stickleback), or pass through the main river corridor to headwaters that are relatively uninvaded by Arundo (southern steelhead). Southern steelhead also reside for part of their life-cycle in estuaries. Arundo impact scores ranged from very high (8) to moderate/high (6). The only federally listed mammal species examined was the San Joaquin kit fox, which resides in the northern part of the study area. It has a very low/improbable (1) impact score from Arundo. The kit fox does not utilize riparian habitat frequently, and is not dependent on it. It may use riparian areas as corridors for movement. Water use, fire, biomass and modification of geomorphology are the primary Arundo impacts on the five plant species examined. Four of the plant species occur on upper portions of the riparian zone (San Diego ambrosia and Nevin’s barberry) or broad areas within the floodplain (San Jacinto crownscale and spreading navarretia). These four species have Arundo impact scores ranging from high (7) to low/moderate (4). San Jacinto crownscale and spreading navarretia occur at a single location within the San Jacinto/Santa Ana watershed, so it is possible to look at very specific interactions for these two species. The fifth plant species, marsh sandwort, occurs in inland freshwater marsh. It is a historic occurrence, so Arundo impacts were projected to the species’ habitat preferences. Although it is unlikely that marsh sandwort still occurs at this location, Arundo is having abiotic and biotic impacts that degrade habitat characteristics favored by the plant. 7.3.1.2 Overlap or Spatial Interaction Scores Overlap rank scores are given in Table 7-3. These were generated by interpreting distribution maps of Arundo and each listed species. Species occurring in downstream portions of the watersheds (river mouth, estuaries, beaches) can receive high scores if significant Arundo infestations occur upstream. Scores ranged from 1 (no interaction) to 10 (very high interaction). Overlap scores captured the interaction between Arundo and each species’ distribution and abundance. Avian species were the widest ranging, with high numbers of watersheds recording occurrences, particularly in the southern and middle of the study area. Fish species also had large numbers of watersheds with occurrences, but more in the middle and northern portions of the study area. Plants were the most restricted, each species typically occurring on only one or two watersheds. 7.3.1.3 Cumulative Impact Scores The Arundo impact score is multiplied by the overlap score to generate a cumulative impact score for each species in each watershed. This metric highlights watersheds, species and taxa groups that are under the most significant pressure from Arundo. The avian group is the most impacted by Arundo, with a score of 1,596 (199.5 average). This is followed closely by amphibians at 686 (171.5 average). The plant group has the lowest score at 298 (59.6 average), largely due to very limited population ranges for the listed species. Mammals also rank very low, being represented by a single species with low abundance and low impacts from Arundo. Several species stand out as having severe cumulative Arundo impact scores across the study area (Figure 7-1). The highest scoring species in the ‘severe’ category are the least Bell’s vireo (702) and the arroyo toad (580). The southwestern willow flycatcher has a ‘very high’ cumulative impact score of 344. The three species are frequently cited as being under significant pressure from Arundo within their ranges. These data strongly supports these accounts. The cumulative impact scores for the fish are ‘very high’ for two species (steelhead and tidewater goby), ‘high’ for the third (Santa Ana sucker) and ‘moderate’ for the fourth species (unarmored three spine stickleback). Arundo impacts on fish have not been recognized in the literature or explored in detailed studies. Arundo’s influence on abiotic processes indicates that significant impacts and degradation are likely occurring on heavily Arundo invaded watersheds. The ‘high’ score for the western snowy plover (160) and the tidewater goby (266), and to a lesser degree the California least tern (72), demonstrate that estuaries, beaches and river mouth areas that support these listed species are impacted by Arundo on a number of watersheds within the study area. This has been alluded to in numerous studies and it appears to be a valid area of concern. Arundo not only degrades riparian habitat, but it also impacts estuaries and beaches, both of which are wetlands of high value and diversity. Watershed totals for cumulative Arundo impact scores clearly demonstrate that those highly-invaded larger watersheds have the most severe impacts to federally listed species (Santa Margarita = 423, Santa Ana = 417, San Luis Rey = 387 and Santa Clara = 326) (Figure 7-2). The Salinas River is the exception, likely due to its more northern position and its lower diversity and abundance of federally listed species. The next tier of highly-impacted watersheds is well separated from the higher tier with scores of 220 for Los Angeles./San Gabriel/Santa Monica and 205 for San Dieguito. The moderate impact tier includes eight watersheds whose cumulative Arundo impact scores range from 161 to 107 (Figure7-2). These include San Juan, San Francisquito/Newport, Sweetwater, San Diego, Ventura, Carlsbad, Santa Barbara, and Salinas. The low cumulative Arundo impact tier includes five watersheds whose values range from 78 to 54 (Figure 7-2).:Estero Bay, Otay, Calleguas, Tijuana, and Santa Cruz/Benito. The cumulative Arundo impact scores highlight watersheds with Arundo impacts to a number of federally listed species. Low ranking watersheds may still have a high cumulative impact for a single species, such as steelhead on the Ventura watershed. 7.3.2 Discussion Arundo impact scores are very severe (10) to moderate/high (6) for 11 out of the 22 evaluated federally listed species. This indicates that Arundo’s modification of abiotic and biotic ecosystem processes is having significant impacts on a wide range of species: Listed fish as a taxonomic group has high impact scores from Arundo. This has not been widely recognized in conservation biology. Listed avian species that fairly exclusively use riparian habitat (least Bell’s vireo, southwestern willow flycatcher, yellow-billed cuckoo) had high impact scores and are recognized as being impacted by fires and habitat degradation. Arroyo toads appear to be severely impacted by Arundo invasion as they are dependent on geomorphic forms and hydrology that are severely degraded by Arundo. Listed plants also had significant impacts tied to specific sites where populations occur. The cumulative impact scores, which account for the interaction in actual distributions of Arundo and the individual listed species, highlight particular species that are under significant pressure within the study area. Five species stand out: least Bell’s vireo, arroyo toad, southwestern willow flycatcher, steelhead and tidewater goby. Arroyo toad, steelhead and tidewater goby have not been previously highlighted as species under significant pressure due to habitat and ecosystem modification by Arundo. The impacts described to estuarine and beach avian species are an important extension of impacts to additional habitat types. These impacts typically rank as moderate to low, but they are well documented as pressures on breeding areas, as well as predation. Prioritization of watersheds by impacts caused by Arundo to federally listed species is complicated. The larger watersheds clearly have the greatest impacts on federally listed species (Figure 7-2). These systems are heavily invaded and are having the most severe modification of abiotic and biotic processes, which is reflected in impact scores. It is interesting to note that three of the four systems also have the most active and comprehensive Arundo eradication programs. These systems have already been prioritized in terms of on the ground activity. Cumulative Impact Score by Species Least Bell's vireo Severe Arroyo toad S.Western willow flycatcher Steelhead Very high Tidewater goby Western snowy plover San Diego ambrosia High Santa Ana sucker Western yellow-billed cuckoo CA gnatcatcher Light-footed clapper rail CA least tern S.Jacinto crownscale Spreading navarretia Moderate Belding's savannah sparrow Unarmored 3spine stickleback CA red-legged frog Mtn yellow-legged frog Nevin's barberry CA tiger salamander Marsh sandwort Low S.Joaquin kit fox 0 100 200 300 400 500 600 700 800 Cumulative Impact Score Figure 7-1. Cumulative Arundo impact score by species for all watersheds. Cumulative Impact Score by Watershed Santa Margarita Santa Ana San Luis Rey Severe Santa Clara L.A./San Gabriel/S.Monica High San Dieguito San Juan San Francisquito/Newport Sweetwater San Diego/Penasquitos S.Barbara/Sth Coast/S.Ynez Carlsbad Salinas Moderate Ventura Estero Bay Otay Calleguas Tijuana Low Santa Cruz/Benito 0 50 100 150 200 250 300 350 400 450 Cumulative Impact Score Figure 7-2. Cumulative Arundo impact scores by watershed for all federally listed species combined. 8.0 COST TO BENEFIT ANALYSIS A cost-to-benefit analysis (CBA) is often used to evaluate the desirability of a given action or intervention. CBAs use a monetary valuation of costs and benefits, which are then expressed as a ratio. This allows the many impacts of an invasive species, such as Arundo, to be synthesized into a common measure, namely dollars. The results can then be used to show how much benefit is obtained by removing the species and where the most substantial benefits accrue. This in turn could help focus control efforts on watersheds or sites with the greatest potential benefit. Multiple CBAs have examined the potential net economic benefit of programs to control Arundo. A detailed examination of benefits related to water savings on the Rio Grande River in Texas found a net benefit four to eight times greater than the cost (Seawright 2009). Broader CBAs covering multiple factors on watersheds within California have found benefit to cost ratios of 3.9:1 for the Santa Clara (Swezey 2008) and 1.1:1 for the Santa Margarita (Hastings et al. 1998). These CBAs were far less intensive analyses compared to the Seawright study. All CBAs for Arundo that could be found showed a positive benefit to cost ratio. Completing a CBA for Arundo control is more straightforward than many that are completed for other types of environmental programs. This is due to reasonably well-defined impacts (potential benefits when Arundo is controlled) and applicable cost valuations. Impacts from Arundo within the study area have been quantified in this report using the mapped spatial distribution of Arundo. This information is used in this CBA, which applies to the entire study area. Cost and benefits are generated for both the peak Arundo distribution and current infestation level (which reflects control work over the past 15 years). A ten-year evaluation period was selected as many impacts are periodic in nature and control programs typically take many years to implement. This CBA is a rudimentary analysis and was not completed by an economist. Many complexities were excluded from the analysis including discounting and depreciation over time. As both the benefits and the costs are accrued on a similar timeline, this simplification is not likely to adversely affect the analysis. Also, unlike other CBA studies (such as Seawright 2009), this CBA did not project future increases in acreage of Arundo (increases the valuation of benefits in the future). For this CBA, the costs of controlling Arundo will be evaluated, and then the benefits will be presented. This includes an analysis for each benefit (impact) class to clearly outline what approach was used in determining valuations. Results are then presented as a Benefit to Cost ratio to determine the net benefit or cost of controlling Arundo within the study area. The higher the benefit is in relation to the cost, the better the economic justification for the action. 8.1 Cost Generating the cost of controlling Arundo for watersheds within the study area is straightforward. The spatial data set gives acreage for Arundo within each watershed, and therefore a good estimate of cost per acre for control is all that is needed. Over $70 million have already been spent controlling Arundo within the study area over the past 15 years. The approximate amount of money spent treating Arundo on each watershed is known as most programs share this information in news updates, proposals and other outreach material. For each watershed treated, acreage and cost of work completed is given in Table 8-1. This data is based on the author’s knowledge of federal, state, and local funding of implementation programs, as well as information published by watershed programs. The average cost is $25,000 per acre of Arundo controlled. This is a strongly supported valuation based on over fifty projects within nine watersheds that have large implementation programs. This cost is subdivided into $5,000 for management and $20,000 for implementation, based on the author’s knowledge of typical cost subdivisions in proposals and reports. Program management costs are high (management of contractors, right of entry agreements, permitting, etc.) as are implementation costs (treatment, biomass reduction, re-vegetation, etc.). It is not surprising that Arundo control is an expensive undertaking given that Arundo stands have high biomass per acre, are difficult to control, and exist in sensitive habitat that is highly regulated. Arundo is also distributed across the landscape making program implementation complex and management intensive. It should be noted that control costs vary substantially between watersheds and projects. This can be attributed to different treatment approaches, how biomass is dealt with, efficiency, and if re-vegetation is included in the project. The $25,000 average cost per acre for control is a well-supported cost estimate for watersheds taken as a whole, or for larger implementation projects. This estimate should not necessarily be used for site-specific projects, particularly if they are small. The total cost of controlling all Arundo at the peak of its acreage would have been $196 million for 7,859 net acres (Table 8-2). A significant amount of control has already occurred, and the current cost of controlling Arundo at current distribution levels is $124 million for 4,997 net acres. Table 8-1. Existing program costs used to generate cost basis for Arundo control by watershed within the study area. Treated Cost per Watershed Expenditure net acres acre Calleguas 1.4 - - Carlsbad 98.7 1,500,000 15,201 Estero Bay 1.2 - - Los Angeles River 16.3 250,000 15,379 Otay - - - Pajaro River - - - Penasquitos 2.2 - - Pueblo San Diego 0.0 - - Salinas 106.4 500,000 4,700 San Diego 56.2 1,000,000 17,798 San Dieguito 89.8 1,500,000 16,701 San Gabriel River 0.0 - - San Juan 13.1 250,000 19,025 San Luis Rey 612.4 7,500,000 12,246 Santa Ana 1006.9 40,000,000 39,724 Santa Clara 0.3 - - Santa Margarita 684.7 10,000,000 14,605 Santa Monica Bay 0.3 - - Santa Ynez - - - South Coast 7.8 - - Sweetwater 5.7 - - Tijuana 41.1 1,500,000 36,496 Ventura River 117.4 7,500,000 63,909 TOTALS: 2861.9 $71,500,000 $24,983 Table 8-2. Estimated control costs by watershed within the study area for peak Arundo levels and current Arundo levels. PEAK Cost peak distribution Cost current infestation CURRENT Watershed Net Management: Implementation: Management: Implementation: Total Net Acres Total Acres 5k 20k 5k 20k Calleguas 229 1,145,750 4,583,000 5,728,750 228 1,138,539 4,554,155 5,692,693 Carlsbad 148 739,472 2,957,889 3,697,362 49 246,088 984,352 1,230,440 Estero Bay 10 48,828 195,310 244,138 9 42,953 171,811 214,764 Los Angeles 131 656,886 2,627,543 3,284,429 115 575,608 2,302,431 2,878,039 Otay 19 92,945 371,781 464,726 19 92,945 371,781 464,726 Pajaro River 8 40,681 162,723 203,404 8 40,681 162,723 203,404 Penasquitos 24 117,737 470,947 588,683 21 106,860 427,440 534,300 Pueblo S.Diego 15 75,009 300,035 375,043 15 74,834 299,336 374,170 Salinas 1,332 6,658,544 26,634,177 33,292,721 1,225 6,126,663 24,506,651 30,633,314 San Diego 149 747,328 2,989,310 3,736,638 93 466,390 1,865,559 2,331,949 San Dieguito 175 874,894 3,499,577 4,374,471 85 425,825 1,703,299 2,129,124 San Gabriel 44 221,535 886,141 1,107,677 44 221,465 885,858 1,107,323 San Juan 173 867,083 3,468,333 4,335,416 160 801,380 3,205,519 4,006,899 San Luis Rey 684 3,419,392 13,677,570 17,096,962 71 357,237 1,428,946 1,786,183 Santa Ana 2,534 12,668,913 50,675,651 63,344,563 1,527 7,634,222 30,536,887 38,171,109 Santa Clara 1,019 5,093,858 20,375,431 25,469,289 1,018 5,092,328 20,369,313 25,461,641 Santa Margarita 689 3,444,463 13,777,850 17,222,313 4 20,972 83,890 104,862 Santa Monica 18 92,430 369,722 462,152 18 90,964 363,857 454,821 Santa Ynez 6 30,104 120,414 150,518 6 30,104 120,414 150,518 South Coast 30 149,075 596,300 745,375 22 110,003 440,014 550,017 Sweetwater 42 208,866 835,464 1,044,330 36 180,474 721,897 902,371 Tijuana 131 653,115 2,612,459 3,265,574 90 447,615 1,790,459 2,238,074 Ventura River 250 1,249,462 4,997,848 6,247,311 133 662,691 2,650,762 3,313,453 TOTALS: 7,859 $39,296,369 $157,185,475 $196,481,844 $4,997 $24,986,839 $99,947,355 $124,934,194 8.2 Benefit The CBA included six Arundo impact classes. Each of these impacts is a 'benefit' when the agent causing the impact (Arundo) is removed. The six classes are: fire, water use, sediment trapping, flood damage, habitat enhancement, and beach debris. 8.2.1 Reduced Fire Impacts (Benefit) Benefits related to reduced fire impacts resulting from Arundo control are presented in Table 8-3. This information is generated from data presented in Chapter 6 on fires that were initiated in Arundo stands, as well as wildfire events that burned Arundo. Arundo-initiated fires have costs associated with fire suppression (Table 8-3). A conservative fire response and suppression cost of $50,000 per event was used in generating cost estimates. The number of events over a ten-year period was based on data for the San Luis Rey watershed. This was then extrapolated to all watersheds based on their acreage of Arundo. Fire suppression costs are related to the number of units responding, work hours spent suppressing the fire, equipment costs, and other support. Fires usually involve multiple units that frequently use air suppression and often have fire lines cut by crews and/or mechanized equipment. The impacts from the fire suppression activities indicate the level of effort exerted during the action (suppression disturbance impacts are outlined in Chapter 6). Arundo-initiated fire impacts to habitat are also included in the cost estimate. The value of burned Arundo riparian habitat is priced lower ($20,000 per acre) then the valuation of un-invaded riparian habitat that burns ($80,000 per acre). These per acre cost valuations are based on mitigation costs associated with restoring riparian habitat, excluding easements and land purchase. Both the actual fire acreage and fire suppression acreage are aggregated in the cost estimate. Arundo-initiated fires were estimated to generate $74.6 million of impacts over 10 years at peak Arundo distribution, and $38.8 million over 10 years at current Arundo levels (Table 8-3). Wildfires represent a potentially open-ended impact class in terms of cost. As discussed in Chapter 6, Arundo stands may be conveying fires across the landscape, linking upland areas and spreading fire into urbanized areas. This seems to have occurred in Santa Clara, where a smaller 8,474-acre fire spread across the river via Arundo stands to the southern mountain range where it burned 107,560 acres. Other fires such as the Freeway Complex fire in Orange/Riverside County and western portions of the Witch Fire in San Diego County may also have had increased fire conveyance as the fires burned through riparian zones containing Arundo surrounded by urbanized areas. Impact costs were hundreds of millions of dollars with large losses to both habitat and developed areas. These landscape-level wildfire costs are too complicated to include in this CBA, but they clearly constitute a significant unmeasured cost that should be partially applied to Arundo. Further documentation needs to occur to more clearly define the role Arundo is having in wildland fires. Wildfires can burn riparian habitat, particularly in firestorm/Santa Ana type events. Arundo-invaded habitat burns during these events along with un-invaded habitat. The Arundo-invaded areas burn much hotter than native vegetation due to the large amount of biomass per acre and the high levels of fuel per unit of biomass (Chapter 6). This results in more intense and complete fires that have a greater impact on the habitat. Post-fire recovery of Arundo stands is rapid, typically resulting in further domination of Arundo in areas that have burned (Ambrose 2007). A valuation of Arundo's degradation of habitat during wildfire events was valued at $2,500 per acre of burned Arundo-invaded habitat. This is an extremely conservative valuation of the impacts to habitat, and it specifically excludes valuation of the fire conveyance impacts that Arundo has during wildfire events. Wildfires that burn Arundo stands were estimated to generate $17.6 million of impacts over 10 years at peak Arundo distribution and $10.4 million over 10 years at current Arundo levels (Table 8-3). 8.2.2 Reduced Water Use (Benefit) Water use of Arundo-invaded habitat was estimated in Section 4.2. Specific adjustments were made for replacement vegetation. Water use and net water savings are exceedingly difficult to validate in field studies, but it seems clear from the high productivity of Arundo (i.e. the very high stand biomass, the high leaf area recorded in studies, and the high water use of C plants in general) that it does indeed 3 have substantially higher water use than native vegetation and/or open areas that would exist in post- control riverine sites. The calculated water savings generated are significant (Section 4.2). It is important to note that most of the areas where Arundo is present within the study area have water available throughout the year. Many watersheds have significant amounts of imported water that generate these year-round flows or, at a minimum, make water tables high enough to support Arundo throughout the growing season. Putting a valuation on water 'saved' after Arundo removal is complicated. In a more comprehensive study, this value would vary by watershed and be based on the specific benefit that the saved water is generating. One key benefit may be the potential for an increase in groundwater recharge. This may benefit domestic use (Santa Ana, Santa Margarita) or heavy agricultural use (Salinas, Santa Clara) of groundwater in a system. For those watersheds (San Luis Rey, San Diego) that have only moderate use of groundwater, the focus may turn to other potential benefits. An increase of water in the riverine system can also benefit habitat and recreation. Longer baseline flows can be critical to several endangered species, particularly on systems with high levels of water management (dams and reservoirs). All of these benefits could be priced out at different rates. For this analysis, a single low value of $50 per acre-foot (ac-ft) of water was used in calculating benefit of water savings. This is a conservative valuation, particularly for southern California. A valuation of $50 per ac-ft of water was the lower end value in the Rio Grande Arundo water use CBA study, with the higher end coming in at $200 per ac-ft (Seawright 2009). Valuations for domestic water use are $527 per ac-ft (Metropolitan Water District) and for agricultural water range from $70 (Coachilla) to $482 per ac-ft (MWD). Much of the water is priced at highly subsidized rates. Nearly all watersheds in the study area import water at a high absolute cost. Additionally, water transfer and pumping costs range from $70–$200 ac-ft (MWD). Water recycling and conservation measures typically cost $70–$150 per ac-ft and are usually considered to be a net benefit. The estimated valuation of water saved over 10 years by controlling Arundo is $78.2 million at its peak distribution and $49.6 million at current distribution level (Table 8-4). Table 8-3. Estimated reduction of fire impacts (benefit). PEAK ARUNDO LEVELS CURRENT ARUNDO LEVELS Fire Started by Arundo Wildfires Fire started by Arundo Wildfire Watershed Habitat Habitat Habitat Arundo Wildfire: Habitat Arundo Wildfire: 50k per damage: 50k per damage: damage: fires 10 yr 500K per damage: rip fires 10 yr 500K per event Arundo event Arundo rip $80K ac total 200 ac $80K ac total 200 ac $20K ac $20K ac Calleguas 115,742 401,857 2,129,655 2,647,254 578,711 115,000 395,814 2,149,120 2,659,934 575,000 Carlsbad 73,947 256,745 1,360,629 1,691,321 369,736 24,609 98,862 459,889 583,360 123,044 Los Angeles 66,394 230,518 1,221,641 1,518,553 331,968 57,561 202,254 1,075,696 1,335,510 287,804 Otay 9,322 32,365 171,519 213,205 46,608 9,295 32,278 173,696 215,268 46,473 Penasquitos 11,810 41,004 217,300 270,114 59,049 10,686 37,407 199,700 247,793 53,430 Salinas 1,003,061 348,263 1,845,632 3,196,956 501,000 100,000 223,336 1,744,000 2,067,336 501,000 San Diego 75,111 260,787 1,382,050 1,717,948 375,557 47,000 169,675 878,336 1,095,011 235,000 San Dieguito 87,491 303,768 1,609,833 2,001,092 437,455 42,582 160,061 795,781 998,425 212,912 San Gabriel 22,281 77,359 409,967 509,607 111,404 22,146 76,929 413,873 512,948 110,732 San Juan 87,575 304,061 1,611,385 2,003,022 437,876 80,138 280,262 1,497,619 1,858,019 400,690 San Luis Rey 341,939 1,187,213 6,291,682 7,820,834 1,709,696 35,724 207,323 667,604 910,651 178,618 Santa Ana 1,361,931 4,728,624 25,059,526 31,150,080 6,809,654 820,000 2,813,396 15,324,160 18,957,556 4,100,000 Santa Clara 540,629 1,877,065 9,947,580 12,365,274 2,703,147 540,500 1,776,596 10,100,864 12,417,960 2,702,500 S. Margarita 344,446 119,592 633,781 1,097,819 1,722,231 - - - 0 0 Santa Monica 9,314 32,340 171,385 213,038 46,572 9,096 31,642 169,994 210,732 45,482 South Coast 14,908 51,759 274,298 340,965 74,538 11,000 39,256 205,575 255,831 55,002 Sweetwater 21,172 73,510 389,567 484,249 105,861 18,047 63,511 337,270 418,828 90,237 Tijuana 67,785 235,350 1,247,246 1,550,381 338,926 47,250 161,674 883,008 1,091,932 236,250 Ventura 165,997 576,341 3,054,344 3,796,682 829,985 94,000 257,212 1,756,672 2,107,884 470,000 TOTALS: $4,420,856 $11,138,520 $59,029,021 $74,588,396 $17,589,972 $2,084,635 $7,027,490 $38,832,856 $47,944,981 $10,424,174 Table 8-4. Estimated reduction of water use by Arundo (benefit). Year Water Use Watershed Peak Arundo Current Arundo levels levels Calleguas 2,290,974 2,290,974 Carlsbad 1,478,605 492,060 Los Angeles River 1,313,470 1,150,950 Otay 185,848 185,848 Penasquitos 235,419 213,650 Salinas 13,314,032 12,250,510 San Diego 1,494,312 932,570 San Dieguito 1,749,387 851,450 San Gabriel River 442,969 442,969 San Juan 1,733,768 1,602,390 San Luis Rey 6,837,215 714,310 Santa Ana 25,332,010 15,264,940 Santa Clara 10,185,377 10,185,377 Santa Margarita 6,887,344 41,940 Santa Monica Bay 184,819 184,819 South Coast 298,082 219,960 Sweetwater 417,636 360,870 Tijuana 1,305,930 895,020 Ventura River 2,498,351 1,325,080 TOTALS: $78,185,547 $49,605,686 8.2.3 Reduced Sediment Trapping (Benefit) As outlined in Section 5.1, it is likely that Arundo has impacts to sediment transport, particularly in low gradient areas where Arundo cover is high (>40%). Many of these areas are highly urbanized, have large-scale agricultural operations, or have significant infrastructure present. Localized sediment trapping is likely occurring in portions of these highly invaded reaches, resulting in loss of flow conveyance. Arundo stands on their own, not even considering sediment trapping, were demonstrated to reduce flow conveyance by five feet where they occurred (Section 5.1). This is a significant loss of conveyance, likely larger than the sediment trapping effect. If these areas are managed for flood risk, agencies (particularly ACOE, municipalities, and counties) may be forced to undertake vegetation reduction or sediment removal to maintain flow conveyance. For example, levees on the San Luis Rey River were designed to contain flows up to a 120–year event. Vegetation and Arundo growth reduced this to a 90–year event capacity (ACOE pers. comm. 2009). This can result in areas being designated as 'high flood risk' (i.e. raising insurance costs) or being designated as uninsurable. Both of these scenarios result in lower property values. When sediment removal and vegetation clearing are not permitted or are considered too costly, the alternative is building new levees or increasing existing levee heights. Both Santa Margarita and San Luis Rey have required either modification or installation of levee structures and/or vegetation reduction programs to maintain flow conveyance. The Salinas River has had channel maintenance activities to reduce flood risk and bank/bridge failure. Other riverine systems in the study area are likely to have had actions in the past and/or will require actions in the future. Cost of implementing vegetation reduction and or sediment removal is also very high. While costs include the removal work itself, this is often a small proportion of the total project cost. Projects typically require complicated regulatory clearance that can take years to obtain, as well as significant mitigation for habitat disturbance/impacts. No specific cost valuation data exist other than the authors’ familiarity with actions carried out on various rivers and the high costs associated with programs undertaking these types of activities. Therefore, valuations assigned in the benefit analysis are again highly conservative. Alternative activities, such as increasing levee heights or constructing new levees are not included here, but these actions do occur and the costs associated with them are high, both in terms of construction cost, permitting and mitigation for permanent wetland loss. True costs of Arundo impacts could be one or two orders of magnitude greater than presented here. The valuation of avoided sediment removal or vegetation reduction costs over 10 years by controlling Arundo was estimated to be $2,500,000 (Table 8-5). Table 8-5. Estimated reduction of sediment trapping (benefit). Sediment Watershed Removal Calleguas $250,000 Carlsbad Los Angeles River $250,000 Otay Penasquitos Salinas $1,000,000 San Diego San Dieguito San Gabriel River $250,000 San Juan San Luis Rey $500,000 Santa Ana $250,000 Santa Clara Santa Margarita Santa Monica Bay South Coast Sweetwater Tijuana Ventura River TOTALS: $2,500,000 8.2.4 Reduced Flood Damage: Bridges (Benefit) Arundo biomass mobilizes during high flow events. This material can contribute or cause loss of structures that cross or are located within (power poles, sewer, gas, and water lines) the river channel. The exact proportion of damage costs associated with the presence of Arundo is difficult to determine. The most easily verified flood damage events involving Arundo are related to massive amounts of Arundo debris that form dams against bridges (Section 5.2.5.1). Loss of bridges has occurred on numerous watersheds that have high levels of Arundo invasion. Not all bridges were observed at the time of failure, but observations of bridges that have been damaged and operations to clear bridges of Arundo during flow events demonstrate that Arundo is a factor. High flow events that mobilize Arundo biomass also move large woody material such as trees. This combination of material collects and backs up against bridge pylons, or if flows are high enough, against the bridge itself. Older bridges with narrow spans are at greater risk of failing. Smaller bridges are also at higher risk as they typically have low clearance and narrow spans. Each watershed was reviewed for bridges (road and rail) that cross over river habitat with significant levels of Arundo around or upstream of them. These bridges were classified into three groups and conservative replacement costs were applied: large ($5 million), medium ($1.5 million), and small ($500,000). These valuations are extremely conservative, as bridge construction often requires costly environmental review and mitigation. Results were multiplied by 20% to estimate the likelihood of bridge loss within the 10-year period and to account for a portion of cost that is due to large flood events taking out bridges regardless of whether Arundo material is in the system or not. The valuation of avoided bridge losses at peak Arundo distribution was estimated to be $24.2 million over 10 years. Control programs have cleared Arundo around and above several bridges, reducing estimated projected impacts to $17.3 million over 10 years (Table 8-6). 8.2.5 Habitat Enhancement (Benefit) As explored in multiple chapters within this report, Arundo has many abiotic and biotic impacts. Some of the most severe impacts to riparian systems are to abiotic processes that are nearly impossible to quantify monetarily in terms of their environmental consequences. Changes to geomorphic form and function, hydrology, water use, and other abiotic functions affect the entire system. Most of the valuations for these types of impacts in previous sections were limited to anthropogenic costs including infrastructure, water for urban and agriculture use, or flood damage. Environmental costs were not included. This CBA will limit valuation of environmental impacts to the degradation of habitat Arundo has invaded. The cost of controlling Arundo is used as a valuation of the habitat benefit (habitat restoration as well and threatened and endangered species’ benefits). A valuation of $25,000 per acre is used to represent the benefit of habitat enhancement/restoration that occurs when Arundo is controlled. This is the same as the cost of the work as outlined in Section 8.1. The total cost is lower, however, reflecting the subtraction of Arundo acreage that was counted under the fire benefits evaluation. This avoids double counting benefits. The use of this valuation is corroborated by the common use of Arundo control as a form of mitigation for impacts to riparian habitat. This is still a slightly conservative valuation as many other forms of riparian 'mitigation' have higher costs per acre ($50,000 to $100,000) for restoration activities, even when land use restrictions (easements or land costs) are excluded from project costs. The total 10 year benefit calculated for habitat restoration/enhancement was estimated to be $181 million at peak Arundo distribution and $110 million for current distribution levels (Table 8-7). Table 8-6. Estimated reduction of bridge losses (benefit) by watershed at peak and current Arundo levels. PEAK ARUNDO LEVELS CURRENT ARUNDO LEVELS Number of Flood Watershed Bridges: Large, Bridge loss or Bridge loss or Flood damage: damage: Medium, & Small damage damage Bridge 20% Bridge 20% Calleguas Med: 8, Sm: 1 12,500,000 2,500,000 12,500,000 2,500,000 Carlsbad 0 0 0 0 Los Angeles River Lg: 1 5,000,000 1,000,000 5,000,000 1,000,000 Otay 0 0 0 0 Penasquitos 0 0 0 0 Salinas Lg: 4, Med: 2, Sm: 1 22,000,000 4,400,000 22,000,000 4,400,000 San Diego Med: 1, Sm: 2 2,500,000 500,000 500,000 100,000 San Dieguito 0 0 0 0 San Gabriel River Lg: 1 5,000,000 1,000,000 5,000,000 1,000,000 San Juan Med: 1, Sm: 1 2,000,000 400,000 2,000,000 400,000 San Luis Rey Med: 4 6,000,000 1,200,000 0 0 Santa Ana Lg: 5 25,000,000 5,000,000 10,000,000 2,000,000 Santa Clara Lg: 2, Med: 3 14,500,000 2,900,000 14,500,000 2,900,000 Santa Margarita Lg: 2, Med: 1 11,500,000 2,300,000 0 0 Santa Monica Bay 0 0 0 0 South Coast 0 0 0 0 Sweetwater 0 0 0 0 Tijuana Sm: 1 500,000 100,000 500,000 100,000 Ventura River Lg: 2, Med: 2, Sm: 3 14,500,000 2,900,000 14,500,000 2,900,000 TOTALS: $121,000,000 $24,200,000 $86,500,000 $17,300,000 Table 8-7. Estimated habitat enhancement (benefit) by watershed at peak and current Arundo levels. Habitat benefit: 25K per ac Watershed PEAK CURRENT ARUNDO LEVELS ARUNDO LEVELS Calleguas 5,226,429 5,190,372 Carlsbad 3,376,431 909,509 Los Angeles River 2,996,281 2,589,891 Otay 424,270 424,270 Penasquitos 537,429 483,046 Salinas 32,857,393 30,197,986 San Diego 3,410,654 2,005,966 San Dieguito 3,994,761 1,749,414 San Gabriel River 1,010,978 1,010,624 San Juan 3,955,339 3,626,822 San Luis Rey 15,612,946 302,166 Santa Ana 57,433,784 32,260,330 Santa Clara 23,122,958 23,115,310 Santa Margarita 17,222,313 104,862 Santa Monica Bay 421,728 414,396 South Coast 680,677 485,319 Sweetwater 952,443 810,484 Tijuana 2,971,387 1,943,887 Ventura River 5,526,884 2,593,026 TOTALS: $181,735,081 $110,217,679 8.2.6 Reduced Beach Debris Impacts from clearing Arundo debris from beaches in southern California was reviewed in Section 5.2.5.2. These costs are based on information collected from municipalities that remove biomass from beaches. Only watersheds that are near beaches and actively remove biomass were given benefit valuations. The estimated 10–year benefit of reduced Arundo biomass on beaches is $1.97 million (Tables 8-8&9). 8.2.7 Total Benefit The total benefit of controlling Arundo at its peak distribution was estimated at $380 million (Table 8-8), and the benefit at its current distribution at $239 million (Table 8-9). This is a conservative valuation because several types of impacts could not be estimated or quantified, and all evaluated impacts were conservatively valued. 8.3 Benefit to Cost Ratio The benefit to cost ratio for peak Arundo distribution was 1.94 to 1 ($380,767,747 to $196,481,844). Current Arundo distribution generates a similar benefit to cost ratio of 1.91 to 1 ($239,461,270 to $124,934,194). A 2:1 return ratio on funds invested is a significant benefit, particularly considering the additional impacts that were not assessed (due to complex valuation), as well as the conservative valuation of factors that were included. A more rigorous CBA carried out for either specific watersheds or the entire project area would likely generate higher benefit to cost ratios. Higher cost valuations of impacts could be documented and defended, and some of the more complicated impacts, which were not included in this CBA, could be explored and included. Table 8-8. Estimated benefits at the peak level of Arundo distribution. Flood Wildfire: Water use Sediment damage: Arundo fires Habitat rest Beach 10 year Watershed 500K per 10 yr removal bridge & 10 yr total 25K debris benefit 200 ac levee Calleguas 2,290,974 250,000 2,500,000 2,647,254 578,711 5,226,429 - 13,493,368 Carlsbad 1,478,605 - 0 1,691,321 369,736 3,376,431 - 6,916,093 Los Angeles 1,313,470 250,000 1,000,000 1,518,553 331,968 2,996,281 328,125 7,738,397 Otay 185,848 - 0 213,205 46,608 424,270 - 869,931 Penasquitos 235,419 - 0 270,114 59,049 537,429 - 1,102,011 Salinas 13,314,032 1,000,000 4,400,000 3,196,956 501,000 32,857,393 - 55,269,381 San Diego 1,494,312 - 500,000 1,717,948 375,557 3,410,654 - 7,498,471 San Dieguito 1,749,387 - 0 2,001,092 437,455 3,994,761 - 8,182,694 San Gabriel 442,969 250,000 1,000,000 509,607 111,404 1,010,978 328,125 3,653,083 San Juan 1,733,768 - 400,000 2,003,022 437,876 3,955,339 - 8,530,006 San Luis Rey 6,837,215 500,000 1,200,000 7,820,834 1,709,696 15,612,946 328,125 34,008,816 Santa Ana 25,332,010 250,000 5,000,000 31,150,080 6,809,654 57,433,784 - 125,975,527 Santa Clara 10,185,377 - 2,900,000 12,365,274 2,703,147 23,122,958 328,125 51,604,881 Santa Margarita 6,887,344 - 2,300,000 1,097,819 1,722,231 17,222,313 328,125 29,557,833 Santa Monica 184,819 - 0 213,038 46,572 421,728 - 866,157 South Coast 298,082 - 0 340,965 74,538 680,677 - 1,394,261 Sweetwater 417,636 - 0 484,249 105,861 952,443 - 1,960,188 Tijuana 1,305,930 - 100,000 1,550,381 338,926 2,971,387 - 6,266,624 Ventura River 2,498,351 2,900,000 3,796,682 829,985 5,526,884 328,125 15,880,026 TOTALS: $78,185,547 $2,500,000 $24,200,000 $74,588,396 $17,589,972 $181,735,081 $1,968,750 $380,767,747 Table 8-9. Estimated benefits at current levels of Arundo. Arundo Wildfire: Water use Sediment Flood damage: Habitat rest Beach 10 year Watershed fires 10 yr 500K per 10 yr removal bridge & levee 25K debris benefit total 200 ac Calleguas 2,290,974 250,000 2,500,000 2,659,934 575,000 5,190,372 13,466,280 Carlsbad 492,060 0 583,360 123,044 909,509 2,107,972 Los Angeles 1,150,950 250,000 1,000,000 1,335,510 287,804 2,589,891 328,125 6,942,280 Otay 185,848 0 215,268 46,473 424,270 871,858 Penasquitos 213,650 0 247,793 53,430 483,046 997,919 Salinas 12,250,510 1,000,000 4,400,000 2,067,336 501,000 30,197,986 50,416,832 San Diego 932,570 100,000 1,095,011 235,000 2,005,966 4,368,547 San Dieguito 851,450 0 998,425 212,912 1,749,414 3,812,201 San Gabriel 442,969 250,000 1,000,000 512,948 110,732 1,010,624 328,125 3,655,399 San Juan 1,602,390 400,000 1,858,019 400,690 3,626,822 7,887,921 San Luis Rey 714,310 0 910,651 178,618 302,166 328,125 2,433,870 Santa Ana 15,264,940 250,000 2,000,000 18,957,556 4,100,000 32,260,330 72,832,826 Santa Clara 10,185,377 2,900,000 12,417,960 2,702,500 23,115,310 328,125 51,649,272 Santa Margarita 41,940 0 0 0 104,862 328,125 474,927 Santa Monica 184,819 0 210,732 45,482 414,396 855,429 South Coast 219,960 0 255,831 55,002 485,319 1,016,111 Sweetwater 360,870 0 418,828 90,237 810,484 1,680,419 Tijuana 895,020 100,000 1,091,932 236,250 1,943,887 4,267,089 Ventura River 1,325,080 2,900,000 2,107,884 470,000 2,593,026 328,125 9,724,115 TOTALS: $49,605,686 $2,000,000 $17,300,000 $47,944,981 $10,424,174 $110,217,679 $1,968,750 $239,461,270 9.0 WATERSHED BASED ARUNDO CONTROL PROGRAMS:

Fund new control on invaded systems, but prioritize where watershed-based programs/ approaches are being used, and where benefit is greatest. Funding is finite, so efficient use of limited resources should occur. Re-treatment of Arundo within established program areas is the highest priority. The fact that Arundo was abundant at these sites prior to control work indicates that these areas have the capacity to support re-establishment of large infestations if left unfinished. Over $70 million has been spent to date on well- established Arundo control programs within the coastal watersheds in the study area. Five watersheds have controlled a significant portion (>80%) of the Arundo found on their watersheds: Carlsbad HU, San Luis Rey, Santa Ana, Santa Margarita, and Ventura. Maintaining and completing Arundo control on the portions of these watersheds treated to date is highest priority. For the most part, funding and management agencies have recognized this and provided funding for re-treatments (years 5 to 20). Continued long-term funding support is needed for re-treatments to achieve true eradication of Arundo within these program areas. Control of Arundo on watersheds with low levels of invasion is the next priority. Some watersheds have low levels of Arundo, most likely due to more recent introductions. Control of invasive plants early in the invasion process is always more cost effective than responding to a larger, more widespread invasion. Programs should be able to control Arundo on many of these smaller populations (Santa Ynez, Estero, Pajaro, and others) with less complicated permitting and low project implementation costs. Treated Arundo biomass can often be left standing if it is scattered, also greatly reducing treatment costs. Funding Arundo control on more invaded watersheds should target watersheds experiencing the most severe impacts coupled with the highest likelihood of achieving success. These rankings are based on impacts caused by Arundo invasion (four classes) and program capacity (two classes, Table 9-2). This ranking approach is biased in that it selects for watersheds that have moderate to high levels of Arundo invasion (due to correlation of impact level and invasion level). Watersheds with low levels of invasion have already been recognized as being of 'high value' for control, even though few impacts may currently be occurring. It should also be noted that the impact classes reflect the magnitude of Arundo's effect on the watershed, not the importance of the impact issue. For example, groundwater recharge and water savings may be a significant issue on a watershed that scores a 0. This low ranking reflects the low Arundo acreage, and corresponding level of impact, but not the importance of water savings on the watershed. Table 9-2 provides guidance in assigning priority among the more invaded watersheds, which may be of use. High ranked watersheds are experiencing severe impacts and have the capacity to implement control. Watersheds with high acreage in the medium class may provide less return on investment in terms of impact reduction. Programs/projects that do not fit into a watershed-based control program should be evaluated carefully. There are situations where control of Arundo at a downstream site can make sense. For instance, control may help protect structures and restore important habitat, or the entity owning the land may have the resources to initiate work. These sites are, however, at significant long-term risk of re-invasion. Funds should be set aside to respond to re-invasion, which is expected to be periodic and varying in intensity. Projects that merely reduce Arundo biomass or only carry out one treatment are not effective long-term control projects, and should not be presented as such. Table 9-2. Arundo treatment priority ranking by watershed. Based on Arundo impacts and program capacity. Total Arundo Impacts Capacity Watershed Percent Group leading Priority Net Total Unit treated control program Water Geo- Listed Exp. Per- ranking Acres Fire Use morph species lead mits Santa Ana 2,534 40% SAWA 5 5 5 5 5 5 30 San Luis Rey 684 90% Mission RCD 4 5 5 5 5 5 29 Lower: USMCB Camp Pendleton, Very Santa Margarita 689 99% 4 5 4 5 5 5 28 Middle: Mission RCD, Upper: none high San Dieguito 175 51% San Dieguito JPA 5 2 4 4 5 5 25 Ventura River 250 47% County of Ventura 3 4 5 3 5 5 25 Santa Clara 1,019 0% No clear lead, multiple parties 5 4 5 5 1 3 23 San Diego 150 38% San Diego River Conservancy 4 2 4 3 4 5 22 Salinas 1,332 8% Monterey RCD 5 5 2 3 3 3 21 High Carlsbad 148 70% San Elijo Conservancy, S.Diego Co 2 2 2 3 5 5 19 San Juan 173 8% County of Orange 2 3 3 3 3 5 19 Tijuana 131 31% SWest Wetlands Interpretive Assoc. 2 2 2 2 4 4 16 Calleguas 229 1% None 3 3 4 2 1 2 15 Los Angeles 131 12% None 2 1 3 4 2 2 14 Calleguas 229 1% None 3 3 4 2 1 0 13 Santa Ynez 6 0% Santa Barbara County Ag Dept 0 1 1 3 5 3 13 Medium Sweetwater 42 14% Sweetwater Authority 1 2 2 3 3 2 13 San Gabriel 44 8% None 1 1 2 4 2 2 12 South Coast 30 26% Santa Barbara County Ag Dept 0 1 2 3 3 3 12 Santa Monica 19 2% None 0 1 2 4 2 2 11 Otay 19 0% None 0 1 2 2 3 2 10 Estero Bay 10 12% None 0 0 0 2 3 3 8 Penasquitos 23 9% None 0 1 2 3 1 0 7 Low Pueblo San Diego 15 0% None 0 1 2 1 0 0 4 Pajaro River 8 0% None 0 0 0 2 0 0 2 Totals:: 7,864 36.4% 10.0 SUMMARY OF DATA FOR ARUNDO: PHYSICAL CHARACTERISTICS, DISTRIBUTION, ABUNDANCE, IMPACTS, AND WATERHSHED CONTROL PROGRAMS’ STATUS AND PRIORITY Conclusions from this impact report are presented below and based on collected data and observations for the greater study area: coastal watersheds in California from Monterey to San Diego (Figure 3-1). Physical Characteristics and Biology  Mature stands are taller than what has been typically reported in the literature: 6.5 m mean, range of 2.6 – 9.9 m. (Section 2.3)  Adjustments need to be made when scaling up from cane-specific data to stand data due to canes not emerging within all areas of Arundo canopy. Areas along edges and gaps within stands have zero to few canes. (Section 2.3)  Biomass per unit area is very high for mature Arundo stands and it is in general agreement with the literature: 15.5 kg/m2. (Section 2.4)  Leaf area of secondary branches is the primary photosynthetic area for older canes, and this constitutes the majority of the mature stand leaf area (75%). This has not been clearly recorded in the literature. (Section 4.1)  Measurements of leaf area (LAI) in mature Arundo stands are very high (15.8 LAI). This is in general agreement with the literature. (Section 4.1)  Additional studies examining LAI and stand structure would further establish that mature Arundo stands have very high LAI. Examination of native riparian vegetation LAI may also be beneficial.  Reviewed literature demonstrates that Arundo spreads through asexual propagation (fragments of rhizomes and infrequently canes). Seeds are not viable. This makes Arundo spread dependent on flood action or anthropogenic disturbance. (Section 2.5)  Review of historic aerial photography indicates that spread of Arundo within a watershed is very episodic- large magnitude (50 to 100–year) events are necessary for the plant to actively invade significant new areas in a riparian system, particularly floodplains and terraces. (Section 2.6.4) These observations are important in that they characterize Arundo stands within the study area. These baseline attributes are used to quantify and explore multiple impacts associated with Arundo in later sections. Arundo Impacts: Transpiration and Water use  Due to high leaf area of mature stands, stand-based transpiration is very high (E 40 mm/day). stand There are two other studies evaluating stand-based Arundo transpiration. One study on the Santa Clara watershed (within this project’s study area) is in agreement (41.1 mm/day). The other study on the Rio Grande River is lower (9.1 mm/day). (Section 4.1).  Stand-based transpiration rates of Arundo, when used to calculate total water over larger areas, indicate very high levels of water use: 48 ac-ft/ac per year. (Section 4.2)  Net water savings for areas after Arundo removal are high (20 ac-ft/yr), even when Arundo water use is lowered 24 ac-ft/ac per yr to reflect levels that may be closer to physiological water transpiration limits. (Section 4.2)  New studies using different approaches to measure stand-based water use of Arundo are needed to corroborate and refine stand-based water use found in this and other studies. New studies need to be on mature stands of Arundo. Stands under treatment or in post-fire or flood recovery should be excluded, as these are not representative of the majority of Arundo stands within the study area. (Section 4.2) Water use by Arundo appears to be a significant impact on invaded systems. Water use by vegetation is difficult to measure. Additional baseline and comparative studies are needed. Distribution and Abundance  Arundo mapping documented a total (gross) of 8,907 acres of Arundo. Net acreage, adjusted for Arundo cover, was 7,864 acres. This represents the peak distribution of Arundo in the study area prior to control activities. (Section 3.2)  Over 3,000 gross acres of Arundo have been treated to date within the study area. This is 34% of the Arundo occurring within the study area. (Section 3.2)  Three large, contiguous watershed units have the highest levels of Arundo control observed in the study area: Santa Margarita at 99%, San Luis Rey at 90% and Carlsbad at 70%. (Section 3.2)  Most other invaded watersheds in the study area with more than 100 acres of Arundo have had at least 30% of their Arundo treated. Noted exceptions to this are Calleguas, Salinas and Santa Clara watersheds, which have less than 10% of their Arundo acreage under treatment. (Section 3.2)  Arundo is most abundant in broad, low-gradient riparian areas where it averages 13% cover. (Section 5.2)  Arundo cover can be very high for large sections (reaches > 0.5 mi long). Arundo was observed occurring at >40% cover on specific reaches on all three watersheds that were examined in detail: Santa Margarita, San Luis Rey and Santa Ana. (Section 5.1) Distribution and abundance data is extremely valuable because it quantifies past and current levels of invasion on watersheds, allows detailed examination and quantification of impacts, and facilitates watershed-based control. Programs can use the spatial data to implement watershed-based control, develop proposals and budgets, and manage control programs. Arundo Impacts: Hydrology and Geomorphology  Mature Arundo stands, due to high cane density, functionally raise the elevation profile by 5 feet, lowering flow capacity. (Section 5.1.4.6)  Arundo stands occur predominantly in floodplain and terrace portions of the river and are nearly absent from the low flow and active channel areas. (Sections 5.1 & 5.2)  Arundo stands on floodplains adjacent to the active channel function as a wall or levee, focusing flows within channel areas. Over time this results in a deepening of the channel and a transformation of the system from a braided unstable channel form to a laterally stable single- thread channel form. (Section 5.1.4.6)  Floodplain areas (floodplains and low terraces) have become much more vegetated on most systems over the last eighty years. This vegetation is both native woody vegetation and Arundo. Mature Arundo stands, however, have much higher stem density and biomass per unit area, generating the observed effects noted above. (Section 5.2.3)  Active channel areas (low flow and bar channel areas with little vegetation) have significantly declined over time on most systems. (Section 5.2.2)  The over-vegetated floodplains and narrow stable deep channels result in modifications of sediment transport and stream power during flow events. (Section 5.1.4.7)  Most riverine systems have become significantly compressed (narrower) over time as terrace and floodplain areas have been permanently separated from the river system with levees that protect both urbanization and agricultural land use. (Section 5.2)  Most riverine systems in the study area have converted from: broad riparian systems with little vegetation cover and channels that were laterally unstable (braided) to narrow riparian systems with highly vegetated floodplains that have a single deep channel. (Section 5.2)  Most Arundo has been removed from the Santa Margarita River for 13 years. The geomorphic response to large flow events in that time has been a significant widening of the low flow and bar channel area (38% increase). Flows also actively pass through floodplain areas; this is a major change in function and process. Moderately-sized events (15 year) now flow through significant portions of channel, bar, and floodplain areas. Before Arundo was removed, flows were restricted to channel and bar areas. (Section 5.2.4)  Loss of flow capacity and presence of Arundo biomass is likely contributing to overbank flows and bridge loss and damage. (Section 5.2.5.1)  Flow events mobilize large amounts of Arundo biomass. Part of this biomass load ends up on coastal beaches where it is frequently removed by public agencies and carries an estimated annual cost of $197,000. This does not include impacts on habitat quality. (Section 5.2.5.2) Hydro-geomorphic impacts are significant. This has ramifications to both the ecosystem and infrastructure in and around invaded rivers. Watershed-based analysis on sediment movement and impacts should be explored in greater detail to further document and quantify relationships. Arundo Impacts: Fires  Arundo stands are highly flammable throughout the year with large amounts of fuel (15.5 kg/m2 of biomass), a large amount of energy (287.1 MJ/m2), and a tall well-ventilated structure with dry fuels distributed throughout the height profile. (Section 6.1)  Fires frequently start in Arundo stands. The primary ignition sources are transient encampments and discarded cigarettes from highway overpasses. (Section 6.1)  Arundo stands strongly attract transient use (dense cover and shelter). This was documented throughout the study area with numerous high use locations noted in both urban and agricultural areas. (Section 6.3.1)  Fires initiated in Arundo stands occur due to fuel and ignition source occurring at the same location. This is a newly defined class of fire events. (Section 6.4.1)  Fires that are initiated in Arundo burn both Arundo stands and native riparian areas. In addition, suppression of fires also impacts riparian habitat. Impacts were calculated for all watersheds using San Luis Rey as a case study. Over a ten-year period for the study area, Arundo-initiated fire events are estimated to have burned 513 acres of Arundo and 706 acres of native riparian habitat. Fire suppression over a ten-year period has impacted 44 acres of Arundo and 32 acres of native riparian vegetation. (Section 6.5)  Wildfires burn a significant acreage of Arundo stands. Over ten years, 6.1% of Arundo stands (544 acres) burned within the study area. (Section 6.5)  Due to high fuel load and stand structure, areas with Arundo burn hotter and more completely then native vegetation during wildfire events. (Section 6.4.2)  Arundo stands appear to be conveying fires across riparian zones- linking upland vegetation areas that would have been separated by less flammable riparian vegetation. This can have catastrophic impacts like those observed in the 2008 Simi fire. The 8,474-acre fire crossed the Santa Clara River and then burned an additional 107,560 acres. (Section 6.4.2)  Arundo fires accelerate the dominance of Arundo in invaded areas due to rapid re-growth and low mortality of Arundo. (Section 6.5.1)  Arundo fire events lead to both direct mortality of wildlife and plants (some of which are sensitive) as well as a longer-term quality reduction of burned riparian areas (post-fire recovery of vegetation and structure). (Section 6.5.2)  Emergency actions tied to Arundo fire suppression also result in impacts (disturbance of both Arundo and riparian vegetation) that degrade riparian habitat and/or may result in mortality of species. (Section 6.5.4) Documentation and separation of Arundo-initiated fires from wildland fires that burn Arundo is an important finding. Impacts from Arundo-initiated fires are common and are the result of Arundo invasion. Harboring ignition sources in combination with combustible fuels year round creates this unique fire risk and impact. This needs to be further studied and documented. If validated, impacts to wildfire spread could be the greatest single impact. Arundo Impacts: Federally Endangered and Threatened Species  Arundo impacts to 22 federally endangered and threatened species from five taxonomic groups varied from: very severe (score of 10) to very low/improbable (score of 1). (Section 7.3.1)  Documented and potential abiotic and biotic impacts from Arundo are described for each species. Abitoic impacts include modification of geomorphology, hydrology, flood disturbance, fire disturbance, water use, and nutrient budgets. Biotic impacts include alteration of vegetation/community structure (displacement of native vegetation), filling in 'open' un- vegetated portions of habitat, creating physical structure that impedes movement, creation of structure in estuaries that facilitates predation, biomass debris that degrades breeding areas, stand structure that is of low value for nesting, and biomass that is of low forage value for both insects and animals. (Section 7.2)  Arundo co-occurs with sensitive species on many watersheds in the study area. This overlap in distribution was evaluated using the Arundo mapping data and sensitive species occurrence data (Appendix B). Interaction between Arundo and each species was scored. Arundo present upstream of sensitive species was specifically accounted for as impacts occur to downstream areas from alteration of sediment loads, geomorphic forms, biomass discharge and other factors. (Section 7.2)  A cumulative impact score was calculated using the species’ specific impact score and the overlap score. This allows each species and each watershed to be evaluated for magnitude of impact. Least Bell's Vireo and Arroyo toad ranked as the most 'severely impacted'. Three species ranked 'very high', four species ranked 'high', ten species were 'moderate', and three species were 'low'. (Section 7.2)  Several fish species ranked very high on the cumulative impact scoring. This is a group of species that have not been closely associated with Arundo impacts prior to this study. Most fish species had impacts related to modification of channel form (single versus braided), channel depth (shallow versus deep), sediment transport, and potential biomass/debris impacts. (Section 7.2)  Estuaries and beaches were shown to have moderate impacts resulting from both Arundo stands, which create physical structure that facilitates predation, and Arundo debris that covers open sandy areas required by ground-nesting avian species. (Section 7.2)  Watershed rankings of Arundo impacts on sensitive species shows that there are four watersheds designated as 'severely impacted', two as ‘highly impacted’, eight as ‘moderately impacted’, and five as ‘lowly impacted’. (Section 7.2)  Three of the four ‘severely impacted’ watersheds have well-developed watershed-based Arundo control programs in place. (Section 7.2) Impacts to habitat are significant. Arundo’s overlapping distribution with sensitive species creates pressures on a wide range of species. Impacts range from abiotic to direct biotic interaction. The most significant impacts relate to abiotic modification of the system (water, fire, geomorphic form), but these are the most difficult to document and quantify due to their scale. Additional research and documentation are needed to increase our understanding of how Arundo modifies ecosystem-regulating processes. Cost to Benefit Analysis  Cost of Arundo control is $25K per acre, as documented by $70 million of work completed on control programs within the study area over the past 20 years. (Section 8.1)  This would total $196 million in control costs at the study area’s peak Arundo distribution and $124 million at current Arundo distribution levels. (Section 8.1)  Benefits from control and reduction of impacts was calculated for fire, water use, sediment trapping, flood damage (bridges), habitat, and beach debris. Analysis was conservative. (Section 8.2)  Benefits: $380 million at peak Arundo distribution and $239 million at current Arundo distribution levels. (Section 8.2)  Benefit to cost ratio of 1.9:1. (Section 8.2) Arundo control is of substantial net benefit. Many impacts were not included in the analysis, and benefits were valued conservatively. The actual benefit of Arundo control is likely much higher than calculated. Watershed Programs  Watershed-based control is a priority and is facilitated by a strong lead entity that manages the program. Effective programs must have the capacity to manage project funds, obtain right of entry agreements, and hold regulatory permits. (Section 9.1)  Permitting is complicated and expensive, but required. Programs with broad and active permits are able to implement programs more effectively and quickly. (Section 9.1)  Watershed programs should use accurate and standardized mapping to represent Arundo acreage. This allows better management of programs, facilitates comparison of projects, and increases accountability. (Section 9.1)  A significant amount of Arundo control has already occurred within the study area and many watershed-based control programs have already formed. (Section 9.1)  Priorities for Arundo control are: (Section 9.2)  Long term re-treatment of program areas that have already had initial control: this protects the investment already made.  Control Arundo on watersheds with low levels of invasion: this eradicates populations before they become abundant, which is more cost effective and avoids future impacts.  Treat watersheds with significant Arundo invasion based on: level of impacts and capacity of groups proposing work. Watershed-based management of Arundo is greatly facilitated by the establishment of a program lead. Programs with tracking systems for work completed, in addition to long-term stability, have the greatest ability of completing true watershed based control (eradication). 11.0 LITERATURE CITED Abichandani, S.L. 2007. 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Detailed Maps of Arundo Distribution Within the Study Area Arundo distribution data from Monterey to San Diego, CA (see Chapter 3 for information on mapping methodology) Spatial data set (GIS geo database) are available for download at: http://www.cal-ipc.org/ip/research/arundo/index.php or http://www.cal-ipc.org/ip/mapping/arundo/index.php The spatial data set is also viewable at the DFG BIOS web site: http://bios.dfg.ca.gov/ Project data sets are named: Invasive Plants (Species) - Central_So. Cal Coastal Watersheds [ds645] Invasive Plants (Prct Cover) - Central_So. Cal Coastal Watersheds [ds646] Arundo donax Distribution and Impact Report APPENDIX B. Occurrence Data and Critical Habitat Areas for Federally Listed Species and Distribution of Arundo. Spatial data for federally listed species includes:  Critical habitat areas designated by USFWS  Occurrence data compiled by the Ventura USFWS Office  Occurrence data from the California Natural Diversity Database (CNDDB: CA DFG)  Additional occurrence data from USGS, SANDAG, and other