Santa Clara River Estuary


SiteSanta Clara River Estuary

MapOxnard 7.5' USGS quadrangle

LocationIn McGrath State Beach - Santa Clara River Estuary Natural Reserve, Ventura County, between the cities of Ventura and Oxnard. Profile information focuses primarily on the area between the ocean and just east of the Harbor Boulevard bridge.

ContactsDepartment of Parks and Recreation, 805-899-1400.

Ventura County Flood Control District, 805-654-2001.

Approximate Wetland Acreage 133
Approximate Historic Acreage 870
OwnershipOwner Acres

California Department of Parks and Recreation (Part of 180 acre McGrath State Beach - Santa Clara River Estuary Natural Reserve) 133

Land Use Designation The estuary is a designated Natural Preserve within McGrath State Beach. It is designated conservation and resource protection in the City of Oxnard 2020 General Plan.
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Onsite UseThe primary purpose of the Natural Preserve designation is to maintain and enhance habitat for native plants and wildlife; there is a trail in the Preserve, and recreational use is limited to passive activities. The estuary receives 8.5 mgd of treated wastewater from an adjacent City of Ventura treatment plant. The Harbor Blvd bridge crosses the River 0.5 miles from the mouth.
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Historic UseSince 1855 gradual encroachment of agriculture, roads, urban development and attendant levees into the floodplain.
Adjacent UseImmediately adjacent to the levee on the north bank are a wastewater treatment plant with a marina beyond, and a golf course east of Harbor Boulevard bridge. To the south are agricultural fields and a state park campground.
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Historic Adjacent Use Roads and agricultural fields had become established by the late 1920's; the wastewater facility, agrigultural fields, Harbor Blvd bridge, and marina, all of which occupy former delta, were in place by the late 1950's.

Tidal Influence A barrier beach forms at the mouth during periods of low flow; it is usually breached by high winter flows and/or wave overwashing, after which the inlet stays open for varying lengths of time.
Watershed Area 1634 square miles
Tributaries and Flow Tributary

Santa Clara River Streamflow is seasonal except for controlled releases and wastewater treatment discharges. In 1996 the 25-yr. flood flow rate was estimated to be 110,000 cfs; it was estimated at 200,000 cfs for the 100-yr. The channel is braided; the banks are reinforced with groins and levees along much of the lower river; there are 3 active out-of-river gravel operations and numerous water diversions, including the Freeman Diversion Dam which crosses the river approximately 11 miles from the ocean.
DamsNone on the Santa Clara River, but on tributaries, Bouquet Reservoir built in 1934, Lake Piru built in 1955, and Pyramid and Castaic Lakes control about 37% of the watershed.
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Other Sources Groundwater

GeneralIncluded in 1996 list of impaired water bodies; coliform standards for contact recreation exceeded. Designated Beneficial Uses are: nav, rec1, rec2, comm, est, mar, wild, rare, migr, spwn, wet. Amphipod survival rates were good in sediment toxicity tests and bivalve survival were good in subsurface and porewater toxicity tests.
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Dissolved Oxygen (DO) 1990 - Morning surface water readings taken throughout the estuary on 4 days July-November, during both open and closed conditions ranged from 7.4 (mouth open) to 18.9 mg/l (mouth closed). Temperatures ranged from 16.7 to 26.2 C.
Water Salinity 1990 - Morning surface water readings taken throughout the estuary on 4 days July-November, during both open and closed conditions ranged from 1.7 (mouth closed) to 33 ppt (mouth open).
SedimentNo information specific to the estuary. A 1989 study estimated that dams and gravel extraction in the watershed had reduced the rate of sand replenishment on the shoreline by 75%. The River's sediment load is described as high during flood flows.

SoilSoils in the marsh area (outside the river channel) are course sand, sand, clay, sandy-clay and loam. In the riverbed, sediment sizes range from silt to gravel.
HabitatAcres Vegetation
River channel/lagoon57.8 (varies seasonally) Not specified.
Diked (nontidal) marsh8.1 1989 - Diverse substrate supporting: common pickleweed, fleshy jaumea, alkali heath, salt grass, fat hen, alkali weed, salt bush, tobacco tree*, Baccharis sp., bulrush, rush, cattail, yerba mansa and cinquefoil.
Undiked marsh1.31989 - Dominated by silverweed, bulrush, common cattail, and curly dock*; jaumea and pickleweed also present.
Riparian57.91989 - Giant reed* abundant, also vegetation assemblages dominated by sandbar willow, spikerush, bulrush, and various willows; poison oak, ragweed, and wild blackberry are among understory species in some areas.
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Scrub/shrub2.9Not specified
Filled wetland5.21989 - Saltgrass

BirdsFall 1994 and Spring 1995 surveys of waterbirds and raptors identified a total of 37 species, including 3 raptors and 5 species of concern. 1996 - Ca Least tern#; 1996 - peregrine falcon.
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FishFall 1994 beach seines of the mouth, center, and back of the lagoon using blocking nets, caught: arrow goby, arroyo chub+, Ca killifish, mosquitofish*, tidewater goby+, topsmelt and yellowfin goby*.
Benthic InvertebratesAugust, November 1989 - 10 cm cores of the lagoon perimeter found only <i>Polydora sp.<i>, a polychaete worm; Oregon mud crab, and <i>Liljeborgia<i>, an amphipod, found on fish traps.
Insect1989 - Midge larvae found on fish traps.
Other Wildlife 1979 - mammal community described as being not very diverse and consisting mostly of rodents, but striped skunk, raccoon, opossum, and coyote are among other animals that use the riparian habitat.
Special Status Species 1994, 1995 - snowy plover, elegant tern, Ca. brown pelican, northern harrier, tidewater goby, arroyo chub; 1996 - Ca. least tern#; 1997 - peregrine falcon.
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Enhancement Status As of winter 1996: a conceptual enhancement and management plan prepared for the estuary in 1990 had not been implemented. The Los Angeles and Ventura County Flood Control Departments were coordinating development of a long-term enhancement and management plan for the entire River and 500-year floodplain.
Watershed Management Included in the Santa Clara River Watershed Management Area which will get focused attention in the FY 2000-2001 watershed cycle by the Regional Board.
PressureEstablishment of exotic plant and animal species, downstream effects of development in the former delta and floodplain and the desire for flood control, alteration of the natural hydrology, and proximity to a well-used recreational area.
CommentsAccess through the lower reaches of the river is critical for steelhead trout migrating to the spawning and rearing habitats in the upper watershed, especially Sespe Creek.

1Swanson, M. L., M. Josselyn, and J. McIver. 1990. McGrath State Beach Santa Clara River Estuary Natural Preserve; restoration and management plan. 75 pp. This report provides a history of land uses, describes current habitat conditions, and proposes management activities for the protection and enhancement of the Santa Clara Estuary. The existing conditions section presents the results of vegetation, water quality, soil salinity, invertebrate and fish surveys done in August and November 1989. The land use discussion includes an analysis of 5 aerial photos covering the period 1929-1987, and an evaluation of the impacts to the estuary caused by contemporary uses of surrounding and upstream properties.

2California Department of Parks and Recreation. 1979. Preliminary general plan: McGrath State Beach. 42 pp. and appendix. This document outlines the scenic, natural and recreational resources of McGrath State Beach and provides recommendations for recreational facilities, given opportunities and constraints posed by both physical factors and user needs. The description of resources contains general unreferenced information on geology, soils, hydrology, plant species and animal use. The appendix includes maps of soils, vegetation, and the area proposed for inclusion in the Natural Preserve.

3Subcommittees of the Santa Clara River Enhancement and Management Plan Project Steering Committee. 1996. Series of separately bound studies. (Available through the Ventura County Flood Control District.) A series of 4 separately bound studies identifying existing conditions and management recommendations for water, aggregate, and biological resources, and flood protection within the 500-yr floodplain of the Santa Clara River. They were prepared by members of the project steering committee and subcommittees to provide the basis for development of the Santa Clara River Enhancement and Management Plan. Please see the following citations.

3aFlood Protection Subcommittee. 1996. Flood protection report, Santa Clara River enhancement and management plan. Approx 50 pp. and appendices. This report describes the river hydrology in terms of past events and the present potential for flooding. It contains a history of flooding and flood protection efforts, and presents a hydraulic analysis, floodplain delineation and description of current and design hydrology, all based on original work. It also identifies flood protection needs and applicable regulations. The study proposes encroachment limits and measures for future flood protection which take into account the dynamic nature of the river, the variety of public and private interests in the river and the need for long-term viability. Appendices contain 1:1,000 scale maps of the entire river showing floodplains and profiles during major historic floods, floodplain boundaries and floodways, and existing and proposed flood protection facilities.

3bAggregate Subcommittee. 1996. Aggregate resources report, Santa Clara River enhancement and management plan. Approx 60 pp. and appendices. Presents the interests of aggregate producers and owners for use in development of the Santa Clara River Enhancement and Management Plan. It identifies objectives for the planning process, describes the existing aggregate supply, demand and active operations, and reviews the institutional and regulatory setting. Recommendations emphasize streamlining the permitting process and identifying areas where extraction might be consistent with habitat and flood control objectives. The report relies on existing information. Relevant regulations and policies are provided in the appendices.

3cUnited Water Conservation District and Castaic Lake Water Agency. 1996. Water resources report, Santa Clara River enhancement and management plan. 83 pp and appendices. Describes the overall hydrology of the Santa Clara River watershed. Information on the river includes the following: climatology, geology, hydrology, water quality and quanity, and water rights. The institutional sitting for the groundwater basins and the surface waters of the river are also described. For each groundwater basin in the watershed the geologic setting, hydraulics, groundwater replenishment areas, fluvial geomorphology, quantity and quality of groundwater, adjudication and rights, and rising and sinking water areas are identified. Recommendations are forwarded to protect groundwater supplies, beneficial uses, existing water rights, and river water quality. Appendices contain precipitation data for 2 stations on the upper river, well water quality and hydrographs for 3 basins in the upper watershed, and flow duration curves averaged over varying periods for 17 stations along the river. Agency comments on the first draft of the report are also contained in the appendices.

3dSanta Clara River Project Steering Committee. 1996. Biological Resources, Santa Clara River enhancement and management plan. Approx 150 pp. plus two volumes of habitat maps. (Not cited in the profile.) The study was conducted in order to describe current biological values along the river and their relationship to adjacent habitats, and to develop management and enhancement actions that would conserve or increase those values. Volume 1 describes vegetative communities and where they occur within the 500-yr floodplain, and identifies special status plant and animal species expected to occur and the likelihood of their presence. The study provides general recommendations for prioritizing areas for conservation and enhancement, assessing impacts, developing mitigation, and developing management programs. Data are drawn from existing information. Volume 2 contains maps of potential habitat for 34 sensitive plant and animal species. Volume 3 contains maps of vegetative communities, distribution of giant cane, conservation values, and potential areas of enhancement and corridor protection.

4Schwartzberg, Beverly J. and Patricia A. Moore. 1995. A history of the Santa Clara River, Santa Clara River enhancement and management plan. 78 pp. (Not cited in the profile) A natural and human history of the Santa Clara River and environs from 1782 to 1990. The period is divided into three eras, and for each, the physical setting, significant natural events, and changes in governance, and land uses are discussed. The study was prepared to help inform contemporary planners developing a management and enhancement plan for the River and floodplain of the historical land use changes that shaped the present river environment.

5California Department of Fish and Game. 1990. Unpublished data sheets, Santa Clara Lagoon water quality sampling. 10 pp. Data sheets from July, August, September and November, 1990 sampling of surface water quality at the Santa Clara River Lagoon. Temperature, pH, DO, conductivity, depth, and salinity were measured in the mornings with a Hydrolab Surveyer II. Notes indicate whether the mouth was open and the tidal stage. The number and location of stations varied according to the amount of water in the lagoon.

6Engle, J. M., K. D. Lafferty, J. E. Dugan, D. L. Martin, N. Mode, R. F. Ambrose, and P. T. Raimondi. 1995. Second year study plan for inventory of coastal ecological resources of the Northern Channel Islands, and Ventura and Los Angeles Counties. Prepared for the California Coastal Commission. 45 pp. A report on the progress and proposed plans for the second year of a monitoring program surveying selected rocky intertidal, soft bottom subtidal, sandy beach, and wetland areas of coastal Ventura and LA Counties, and the Northern Channel Islands. The discussion emphasizes program design and methods with some analysis of first year results. The LA/Ventura County portion focuses on wetlands, with fish, invertebrate, and bird surveys to be conducted at: Ventura and Santa Clara River estuaries, Ormond Beach, Mugu Lagoon Malibu Lagoon and Ballona wetlands. Other habitats will be characterized by samples at 20-30 additional sites. The study is being undertaken to enable an assessment of impacts in the event of an oil spill.

7Ventura Audubon Society. 1996. Final report, California least tern breeding survey 1996. 6 pp. This is a brief monitoring report prepared in the form of responses to a questionnaire. Dates are provided for the progression through critical breeding stages, and numbers of nests, eggs, and fledglings are noted. The condition of nesting sites with respect to the degree of protection, preparation, and potential predators in the area is described. Disturbances to the nests and evidence of mortality are also identified.

8Holderman, Reed. California State Coastal Conservancy. December 5, 1996. Personal communication.

9California Regional Water Quality Control Board, Los Angeles Region. 1994. Water quality control plan Los Angeles Region (4). 187 pp., plus appendices. The Los Angeles Regional Board's Basin Plan is designed to preserve and enhance the water quality and protect the beneficial uses of all regional waters. The plan designates beneficial uses and associated water quality objectives for inland surface waters, ground waters, coastal waters, and wetlands for Los Angeles and Ventura Counties. It includes a discussion of applicable policies and statutory requirements, and identifies measures for achieving water quality objectives. It also describes ongoing monitoring and assessment programs.

10Los Angeles Regional Water Quality Control Board. 1996. Water Quality Assessment and Documentation. 106 pp. A list of waterbodies in the Los Angeles and Ventura County coastal watersheds that do not or are not expected to attain water quality standards after application of required technology-based controls. It includes a description of the methods and criteria used in the assessment. 303(d) lists are prepared as part of the Water Quality Assessment of the State's major waterbodies, and meet a requirement of Section 303(d) of the federal Clean Water Act.

11Saiki, M. K. 1994. Survey of fishes and selected physicochemical variables in Mugu Lagoon and its tributaries, September-November 1993. 65 pp. and appendices. This document reports the results of fish surveys conducted to determine the status of the tidewater goby in Mugu Lagoon, and to examine the relationships among physicochemical conditions and the abundance and distribution of all species caught in the lagoon. Throw nets, bag seines, minnow seine and dip nets, all of 3.2 mm mesh, were deployed September-November 1993, at 27 stations in Mugu Lagoon and it's tributaries, and at 2 stations in the Santa Clara River estuary. Temperature, pH, DO, salinity, turbidity, and sediment particle size were also sampled. Stations in the Santa Clara River, where tidewater goby were known to be present, served as a check on sample methods and as a basis for comparison of habitat conditions. A series of scatter plots display relationships among various sediment and water quality parameters and occurrence of fish species. Appendices contain raw data and maps showing the stations where each species was caught.

12City of Oxnard. 1990. 2020 General Plan. Approx. 300 pp. The comprehensive long-term general plan for physical development of the area within the City's jurisdiction, or areas beyond City jurisdiction which have bearing on its land use planning activities. It describes the current setting and presents findings, policies, and implementation strategies for growth management, land use, circulation, public facilities, open space/conservation, safety, and noise issues. Biological information is based on existing information and provides few references.

13Biroski, S., California Regional Water Quality Control Board - Los Angeles. March 11, 1997. Personal communication.

14Pritchett, D. A.; US Fish and Wildlife Service, Ventura Field Office. March 1997. Personal communication.

15Lafferty, K. D.; UC Santa Barbara, Marine Science Institute. April 1997. Personal communication.



This file last modified on: Tuesday, December 2, 1997.
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