Ocean and Coastal Policy Center

28

Section 2

29

Watersheds and Wetlands in Los Angeles Basin subregion

WATERSHED

Santa Ana Hydrologic UnitSan Diego CreekSanta Ana River

San Gabriel River

Los Angeles River

Ballona Creek

WETLANDS

Upper Newport Bay, San Joaquin MarshSanta Ana River EstuaryHuntington Beach WetlandsBolsa Chica WetlandsAnaheim Bay

Los Cerritos Wetlands

Ballona Wetlands

The watersheds and wetlands in this subregion share several problems attributable to the extensive degree of urbanization in the watershed, including:

• Loss of riparian and floodplain habitat as a result of channelization and under-grounding of stream corridors.

• Increased storm runoff quantity and peak flows due to increased imperme-able surfaces in the watershed. This has contributed to increased channel incision and bank erosion with loss of riparian habitat and increases in downstream sedimentation.

• Decreased water quality, including increased loads of sediments, nutrients, metals, and organic compounds, and increased water temperature.

Newport and Anaheim Bay

Of the wetlands in the subregion, Upper Newport Bay and Anaheim Bay support some of the healthiest wetlands in southern California. Upper Newport Bay includes more than 900 acres of wetland habitat, and supports popula-tions of the California light-footed clapper rail, Belding’s savannah sparrow, and California least tern. The major areas of concern for the Upper Bay are sedimentation, bacterial contamination, toxics, and nutrient inflows, which contribute to eutrophication. Anaheim Bay is part of the Seal Beach National Wildlife Refuge and is located within the boundaries of a U.S. Naval Weapons Station. Approximately 956 acres of wetlands remain at Anaheim Bay, and numerous species of concern use the site.

Bolsa Chica

Diking, filling, oil extraction activities, and other anthropogenic impacts have signifi-cantly degraded wetlands in this subregion. Despite land-use activities within the watershed, the Bolsa Chica wetlands complex is an incredibly diverse ecosystem that includes a range of invertebrate, reptile, bird, fish and other species. A compilation of 15 surveys from 1970 through 1993 identified 206 species, including 129 water related species and 32 special status species. A partnership of eight state and federal agencies is coordinating a project to restore approximately 880 acres of the Bolsa Chica Wetlands. Mitigation monies from the Ports of Los Angeles and Long Beach are partially funding the project. Major portions of the Santa Ana River estuary, Huntington Beach wetlands, Los Cerritos Wetlands, and Ballona Wetlands are privately owned, which currently limits wetlands restoration opportunities.

The Santa Monica Mountains subregion differs substantially from the highly urbanized Los Angeles Basin. This subregion area totals approximately 240 square miles, and is primarily open space. The subregion has over 20 coastal drainages, which are characterized by relatively short, steep watersheds with little or no wetlands habitat at the mouth. Average rainfall in the subregion is 24 inches per year. Several creeks in this region support steelhead runs, or did so historically. A list and brief characterization of wetlands and watersheds of the subregion are found below.

Key Watersheds and Wetlands in the Santa Monica Mountains subregion

WATERSHED

Santa Monica Bay Hydrologic UnitTopanga CreekMalibu CreekSolstice CreekTrancas Creek

WETLANDS

Topanga LagoonMalibu Lagoon

Trancas Lagoon

In comparison to most of the other subregions, the watersheds in the Santa Monica Mountains are in relatively good shape. For this reason, the focus in this subregion is on the preservation of existing habitat and stream functions, rather than on restoration. Key issues for this subregion include:

• Impacts of increased development on watershed processes and functions, includ-ing increased channel and bank erosion.

• Preservation and/or restoration of steelhead habitat and removal of fish passage barriers.

• Exotic species infestations, primarily Arundo donax.

Malibu Lagoon

The most important wetland in this subregion is Malibu Lagoon. There are approxi-mately 92 wetland habitat acres. Historical estimates of total wetland acres are several times its present size. Key issues at Malibu Lagoon include poor water quality, restricted tidal circulation within the lagoon, and increased freshwater inflows during the dry season. A task force of federal, state, and local agencies is working on a multi-year effort to restore the lagoon and lower reaches of Malibu Creek.

Santa Monica Mountains Subregion

The Ventura County Basin is a subregion that extends from Mugu Lagoon to the Ventura River, and includes some of the region’s healthiest riparian and wetland habitats. Riparian vegetation is common along the two major watersheds associated with the Santa Clara and Ventura Rivers. Both watersheds include suitable spawning habitat for steelhead trout. Primary wetland areas in the subregion lie at the mouths of the Ventura River and Calleguas Creek. Mugu Lagoon is the largest estuarine lagoon in southern California. The Santa Clara River is the largest river system in the region with extensive riparian habitat. These riparian habitats serve as an important stopover for migratory bird species. Like the other subregions, develop-ment and suburban sprawl within watersheds is increasing erosion, sedimentation, and pollution. In addition, pesticides have accumulated in aquatic life and sediments.

Ventura County Basin Subregion

Western Screech Owl

©H

ugh

Smith

Jr.

Great Horned Owl nestlings

©M

organ Ball

Ocean and Coastal Policy Center

30

Section 2

31

There are also threats to water quality and habitat degradation posed by increasing encroachment by development with the Santa Clara River watershed and the Oxnard Plain. A list and brief characterization of wetlands and watersheds of the subregion are found below.

Watersheds and Wetlands in the Ventura Basin subregion

WATERSHED

Calleguas CreekTopanga Creek

Oxnard Plain

Santa Clara River

Ventura River

WETLANDS

Mugu Lagoon

Ormond Beach

Santa Clara River EstuaryMcGrath Lake

Ventura River Estuary

The focus in this subregion is on the preservation of existing habitat, such as the riparian areas and woodlands that exist along the Santa Clara River and its floodplain, and the removal of dams that block the passage of steelhead trout to the headwaters of the Ventura River. The aquatic habitats and species that depend on the Mugu Lagoon remain threatened by water quality concerns associated with Calleguas Creek. A planning process to remove dams and other barriers for steelhead passage within the upper watershed of the Ventura River continues. Key issues for this subregion include:

• Preservation and/or restoration of steelhead habitat and removal of fish passage barriers.

• Decreased water quality, including increased loads of sed-iments, nutrients, metals, and organic compounds, and increased water temperature.

• Encroachment of development and loss of wetland and supporting upland habitat.

Calleguas Creek and Mugu Lagoon

Calleguas Creek drains a predominantly agricultural area in the Oxnard Plain. Develop-ment within the watershed has caused severe erosion and sedimentation. High levels of minerals and nitrates are common in the water column as well as in the groundwater. In addition, discharges from sewage treatment facilities contribute excess nutrients into Mugu Lagoon. DDT, PCBs, other pesticides, and some metals have been detected in both sediment and biota collected from surface water bodies of this watershed. Despite water quality problems, Mugu Lagoon remains one of the highest quality wetlands remaining in California, and supports the greatest concentration of water-associated birds north of Anaheim Bay. In addition, Mugu Lagoon is recognized as the closest large mainland roost to the major breeding colony and night roost of California brown pelicans at Anacapa Island, and serves as a staging area for birds and seals moving to and from the island. Approximately 1,474 acres of wetland habitat are found at Mugu Lagoon.

Ormond Beach

As part of the historical wetlands complex of the Oxnard Plain, Ormond Beach wetlands contain 217 acres of habitat along a one-mile stretch of the coast. The majority of wetlands at Ormond Beach are not directly tidally connected, but historically they were probably connected to Mugu Lagoon through channels and sloughs, which

provided limited tidal influence. Although these fragmented wetlands are for the most part highly degraded, they are still providing valuable wildlife habitat and have a high potential for restoration. Poor water quality in the adjacent drainage channels and possible contaminated groundwater from proximate industrial facilities contribute to the degraded status of the wetlands. The use of off road vehicles along the beach and dunes area is a major disturbance to wildlife. Additionally, pressure to convert farmlands north of the wetlands to urban uses could increase the amount of non-point source contaminants entering the marsh areas.

Santa Clara River

The Santa Clara River is the largest unchannelized riverine system in the south coast. The watershed encompasses approximately 1,200 square miles. Extensive patches of high quality riparian habitat are present along the length of the river and its tributaries. One of the largest of the Santa Clara River’s tributaries, Sespe Creek, is designated a wild trout stream by the State, and supports significant spawning and rearing habitat. Piru and Santa Paula Creeks also support good habitats for steelhead. The watershed provides habitat for a wide range of threatened and endangered species. Encroaching development in the floodplain and proposed channelization and other flood control activities threaten the health and integrity of riparian habitat within the watershed.

Ventura River

The Ventura River watershed encompasses 228 square miles, and is 31 miles long from upper Matilija canyon to the Pacific Ocean. The Ventura River ecosystem supports 23 species of special concern. In addition to the steelhead, these species include the California condor, California red-legged frog, and California Brown pelican. The major issue within this watershed is the dramatic historical decline of the southern steelhead, which is an indication of the general health of the aquatic ecosystem. The removal of Matilija Dam on Matilija Creek, a tributary to the Ventura River, would help to restore the salmon to this watershed. Constructed in 1948, the dam is located 15 miles from the ocean within Los Padres National Forest. Removal of Matilija Dam would provide fish passage to historic breeding waters in the upper watershed, and greatly enhance the opportunities for restored habitat for the other species of concern.

Southern Santa Barbara County Coastal Watersheds Subregion

The subregion of the southern Santa Barbara County watersheds extends from Rincon Point to creeks of the Gaviota coast. Several creeks flow onto the narrow coastal plain between Goleta and Rincon Point, and support riparian habitat of varying size and

vigor. The subregion also contains aquatic habitats along the coast, such as vernal pools. The coastal watersheds and wetlands of the region remain threatened by human disturbances because many wetlands are in close proxim-ity to urban and commercial developments. A list and brief characterization of wetlands and watersheds of the subregion are found below.

Greater Roadrunner with Western Fence Lizard

©H

ugh

Smith

Jr.

Bullock’s Oriole male

©M

organ Ball

Ocean and Coastal Policy Center

32

Section 2

33

©M

orga

n Ba

ll

Watersheds and Wetlands in the Southern Santa Barbara subregion

WATERSHED

South Coast Hydrologic UnitRincon CreekFranklin Creek

Goleta Slough (Atascadero, San Jose, Las Vegas, San Pedro, Carneros, Tecolotito Creeks)

Devereux CreekGaviota Coast Creeks

WETLANDS

Carpinteria Salt MarshGoleta Slough

Devereux Slough

The coastal creeks and watersheds of southern Santa Barbara County are associated with the south facing Santa Ynez Mountains. These coastal watersheds and associated wetlands are unique in the context of southern California since they are located in an ecotonal area, where the northern and southern California biological provinces meet. The subregion is the northernmost boundary for many species of southern California. Restoration plans are currently being implemented in the three major wetlands of the subregion, Carpinteria Salt Marsh, Devereux Slough and Goleta Slough. The major concerns within the subregion are the preservation and restoration of wetland habitat, the protection of native species diversity, and address-ing water quality concerns. Key issues for this subregion include:

• Preservation and/or restoration of steelhead habitat and removal of fish passage barriers.

• Adjacent development, siltation, and reduction of fresh-water inputs.

• Decreased water quality, including increased loads of sed-iments, nutrients, metals, and organic compounds.

• Encroachment of development and loss of wetland and supporting upland habitat.• Changes in mammalian predator populations.

Carpinteria Salt Marsh

The sub-watershed encompasses 6,600 acres, and includes the tributaries of Santa Monica and Franklin Creeks (and a smaller unnamed drainage to the west of Santa Monica Creek). Carpinte-ria Marsh is situated in a context of residential development. Both Santa Monica and Franklin Creeks are tidally influenced through the marsh to the Pacific Coast Highway. The Carpinteria Salt Marsh is one of the most important wetlands in this subregion. The marsh is typically tidally influenced, but a barrier bar forms some years at the ocean inlet. The bar is then mechanically breached to maintain year round tidal flushing. At least 190 bird species, 37 fish species, 11 mammal species, 5 herpetofauna species, and over 100 invertebrate species have been observed, collected, or reported from Carpinteria Salt Marsh. The marsh is the northwestern geographic limit for many species (e.g., Estero Seepweed, Shoregrass, Belding’s Savannah Sparrow, and Light-footed Clapper Rail). Water quality that drains to the marsh is impaired from pesticides, siltation, nutrients, and urban run-off. Non-native predators, typical of suburbanized watersheds, continue to be a threat to nesting birds and other wildlife. The watershed is in poor condition for steelhead passage; there remain many barriers and culverts in the upper part of this watershed.

Goleta Slough

The Goleta watershed encompasses 45 square miles. The tributaries of the watershed include Tecolotito, Carneros and Atascadero Creeks. The Goleta Slough includes 430

acres of an approximate historic acreage of 1,150, and is almost entirely sur-rounded by urban development, some of which extends into the wetlands. In 1996, 279 species were identified at Goleta Slough of which 121 species were water-associated, including 20 species of special status. In a 1994, 117 pairs of Belding’s Savannah sparrows were observed nesting in the slough. Public utility and transportation corridors traverse the wetlands, and airport runways, a sanitary treatment plant, a power generation station, and light industrial facilities are constructed on filled portions of the marsh. Continued sediment deposition is reducing the tidal prism. Due to limited buffer areas along the perimeter of the wetlands, wildlife is disturbed by highway traffic and activities in the developed areas. Several creeks within the watershed provide habitat suitable for southern steelhead restoration, but there remain several flood control dams, diversion dams, and culverts that prevent passage. Water diversions, small berms at the mouth of most creeks, and excess sediment have been noted in several creeks that could support a steelhead run.

Devereux Creek

The southern part of the Gaviota Coast includes the Devereux Creek watershed. The watershed area encompasses 2330 acres. Devereux Slough is located on the West Campus of the University of California at Santa Barbara. The approximate wetland habitat acreage is 70. Historically, the slough is estimated to have been approximately 2 to 3 times its present size. The slough is tidally influenced only during short periods in the winter. A beach berm forms at the mouth of the slough during drier months. Biological inventories have identified 290 species associated with the slough and Coal Oil Point Reserve of which 118 are water-associated, including 15 species of special status. The white-faced ibis was recorded as nesting. Sediment loading is reducing the total size of the slough. Continued residential development in the watershed may increase contamination of runoff and sediment entering the slough. Exotic plant species are displacing native plants and altering the habitats.

Gaviota Coast Creeks

The importance of this coastal stretch of southern California is reflected in the fact that the area between Coal Oil Point and Point Sal comprises only 15% of Southern California’s coast yet holds approximately 50% of its remaining rural coastline. This area includes relatively healthy coastal watersheds and wetlands because of the general lack of urban and suburban development.

The main coastal ecosystems and watersheds on Vandenberg Air Force Base (VAFB) include the Santa Ynez River and the San Antonio Creek. These coastal ecosystems remain important nurseries to the sea, and are important to the health and integrity of the marine system of the Southern California Bight. VAFB is located in a transitional ecological region that lies at the northern and southern distributional limits of many plant and animal species. The base provides habitat for many special-status species, including federal- and state-listed threatened and endangered, proposed listed, and candidate plant and animal species as well as species of special concern. Recently, 14 major vegetation and habitat types were described and mapped on the base. More than 850 plant species, 53 mammal species, 315 bird species (115 breeding), 17 reptile species, and

Great Blue Herons courtship

©H

ugh Smith Jr.

Wandering Tattler©

Morgan Ball

Snowy Plover chick

Green Heron

Ocean and Coastal Policy Center

34

5J.A. Gallo, J.A. Scheeter, M.A. Holmgren, S.I. Rothstein. 2000. Avian Point Counts and Habitat Assessment in Riparian Communities in 1998 at Vandenberg Air Force Base. UCSB Museum of Systematics and Ecology. March.

10 amphibian species are found in these habitat types (U.S. Air Force 1997).The Santa Ynez River and San Antonio Creek are two major drainages, each with associated riparian and wetland habitats. Closely related to these habitats are adjacent transitional and upland habitats. Coastal marsh and lagoon habitats occur near the mouths of these two bodies of water where they drain into the Pacific Ocean. This variety in habitat types, in a relatively small area, provides the setting for a large diversity of plant and wildlife species.The Santa Ynez River is the largest watercourse on VAFB. A 400-acre lagoon, ringed with tidal wetlands and mudflats, lies behind the sand bar that forms at the river mouth during the summer months (OTA 1982). Salt and freshwater marshes are also part of this wetland complex. The river once sus-tained an abundant wild southern steelhead run.The San Antonio Creek drainage extends from northeast of the town of Los Alamos to the San Antonio lagoon at the Pacific Ocean. Land uses in the Los Alamos valley upstream of VAFB are agricultural and include field crops, vineyards, and grazing lands. In the upper watershed, the vegetation community changes from intermittent riparian to coast live oak and valley oak. Upland habitats along San Antonio Creek include coastal sage scrub, coastal dune scrub, and nonnative grassland. Other vegetation includes nonnative grasses, shrubby scrub, disturbed roadside vegetation, and agricultural fields. The habitats adjacent to San Antonio Creek are considered wetlands, and are either willow riparian woodland or freshwater marsh habitat. Most of the vegetation found in these areas consists of facultative or obligate wetland species. The San Antonio Lagoon also includes freshwater and coastal brackish marsh habitats, which occur along with coastal strand habitat. The diversity of fauna in this area may be attributed to the variety of habitat types along and adjacent to San Antonio Creek. Willow riparian woodland supports a wide variety of birds, due to the cover, foraging habitat, breeding and nesting habitat, and perch sites provided by the willow woodland5. In addition, several fish, reptile, amphibian, and mammal species use the upland and riparian habitats associ-ated with San Antonio Creek for residence and migra-tion corridors.Although VAFB contains extensive biological resources, disturbance from human activities such as agriculture, cattle grazing, groundwater withdrawal, road and other development, and exotic species introductions have resulted in the degradation of native upland and wetland species. Impacts of these disturbances have been noted in many parts of the base, including San Antonio Creek and the El Rancho Road Project area. The disturbances have resulted in changes in the creek’s flow regime and shifts in vegetation types.

Ross’s Goose

Rare dune flowers on Vandenberg Air Force Base

©M

organ Ball