San Dieguito Lagoon

GENERAL			Source
Site	San Dieguito Lagoon
Map	Del Mar USGS 7.5' quadrangle
Location	20 miles north of San Diego Bay, at the northern edge of the City of Del Mar.
Contacts	California Coastal Commission, San Diego coast area office (916) 521-8036
	San Dieguito River Park Joint Powers Authority (619) 235-5445
Approximate Wetland Habitat Acreage	260		4
Approximate Historic Acreage	600		9

Ownership	Owner	Acres	Source
	California Department of Fish and Game	approximately 98	3
	San Dieguito River Park Joint Powers Authority	60.37	13
	San Diego County	144	13
	City of San Diego	approximately 49	8
	22 District Agricultural Association (includes some uplands, does not include fairground)	87	6, 3
	North County Transit District	4.5	3
	Private	100 +	6, 3

LAND USE			Source
Land Use Designation	City of Del Mar - mostly Floodway; small areas of North Commercial/Floodplain Overlay and Public Parkland/Bluff, Slope, Canyon Overlay. City of San Diego - Open Space, A-1-10, and Sensitive Coastal Resource Overlay.		11, 12
Onsite Use	Hwy 1, Jimmy Durante Blvd, I-5, and railroad tracks cross the lagoon with Hwy 1 spanning the mouth; there is a State Ecological Reserve in the "fishhook" area of the lagoon which provides some public access; some areas east of I-5 are in agriculture.		4, 9
Historic Use	Native American middens dated approximately 50,000 years old. Sewage was discharged into oxidation ponds and into lagoon channels 1940-1974; an area between the channel arms supported an airfield and light industry 1942-64,		9, 4, 17
	(a Coastal Commission study dates airfield construction to the 1920's) farming has occurred at different periods at various sites east and west of I-5 since the 1920's.
Adjacent Use	Scripps Bluff Preserve, Del Mar Racetrack and Fairgrounds, a golf driving range, and Via del Valle lie immediately to north; El Camino Real, agricultural and residential uses are found to the east; bluffs, Crest Cyn		4, 9, 2
	Park, and residential development are south of the lagoon; commercial and residential uses and the beach form a western boundary.
Historic Adjacent Use	Native American middens dated at approximately 50,000 years old. Agriculture and gradual encroachment and fill for existing onsite uses, including the race track and fairgrounds built in 1935.		4, 9

HYDROLOGY			Source
Tidal Influence	The constrained ocean inlet, railroad berm and I-5 restrict tidal influence, and accumulated sand can block the mouth for extended periods; between March 1992 and May 1993 the mouth was closed 9 months,		4, 15, 16
	it remained open 19 of the 22 succeeding months (data through March 1995). The tidal prism was 184 ac-ft in 1984.
Wetland Watershed Area	345 sq miles, 302 of which are behind dams.		10

Tributaries and Flow	Tributary	Flow	Source
	San Dieguito River	Flow is intermittent and the river bed upstream of tidal influence is often dry. The channel is substantially unarmored except for a concrete block revetment along the upper bank from approximately Jimmy Durante Blvd to the	4
		ocean. The average recurrence for major floods is 10-15 years; major flooding occurred in 1993, resulting in continuous flows January to May with a peak rate of 10,000 ac-ft/day.
Dams	Lake Hodges, completed in 1919 and Lake Sutherland completed in 1954.		5
Other Sources	Three tributaries join the San Dieguito River below the dam; 2 other small drainages empty directly into the lagoon basin.		9

WATER QUALITY			Source
General	Dependent upon tidal influence and freshwater flows. Water quality was monitored between March 1992 and May 1993, during which time the mouth was intermittently open for 2 months, closed for nearly 8 and open for nearly 5 after heavy flooding.		4, 18, 19, 20
	Not listed as impaired. Designated Benefical Uses: rec1, rec2, biol, est, wild, rare, mar, migr
Dissolved Oxygen (DO)	The range of surface concentrations of D.O. in tidal creeks March 1992 - May 1993 was approximately 1.5-15.5 mg/l; the range for the entire site (7 habitats, 12 stations) was approximately .5-24 mg/l. Samples were taken at various times of the day.		4
	Readings below 4 mg/l were recorded when the lagoon inlet was closed. The temperature range of tidal creek surface waters was approximately 17-30 C; the range for the site was approximately 16 - 30 C.
Water Salinity	The range of surface salinity levels in tidal creeks March 1992 - May 1993 was 6 - 47 ppt; the range for the site (7 habitats, 12 stations) was approximately 0 - 47 ppt.		4
Sediment	Sand and gravel input to the river is estimated to be at 20% of normal due to dams; Lake Hodges is assumed to trap 100% of the sediments carried into it.		4

Soil			Source
Soil	Unconsolidated alluvium; Chino silty loam saline, Corralitos loamy sand, tidal flats, Tujunga sand, and fill including concrete foundations, were identified in marsh and transitional areas.		4

Habitat	Acres	Vegetation	Source
Open Water	85.67	May 1992, April 1993 surveys - Unspecified algae	4
Estuarine/ Palustrine flats	30.51	Non-vegetated	4
Salt marsh (acreage is for defined study area, generally the area below 10 ft NGVD; an additional 5.37 acres of salt marsh were identified in the vicinity but not surveyed for vegetation)	112.76	May 1992, April 1993 surveys listed pickleweed, saltgrass, alkali heath, glasswort, sicklegrass* and sweet clover as characteristic, also 7 colonies of transplanted cordgrass; habitats included areas described as seasonal and transitional.	4
Brackish/freshwater marsh (acreage is for defined study area, generally the area below 10 ft NGVD; an additional 9.19 acres were identified in the vicinity but not surveyed for vegetation)	6.52	May 1992, April 1993 surveys listed spiny rush, alkali bulrush, tall umbrella sedge, spike rush, and cattail as characteristic.	4
Riparian scrub	9.86	May 1992, April 1993 surveys identified mulefat, arrowweed, and southern willow communities.	4
Transition (acreage is for defined study area, generally the area below 10 ft NGVD; an additional 411.11 acres of transitional communities were identified in the vicinity but not surveyed for vegetation)	217.6	May 1992, April 1993 surveys listed ice plant, sweet clover, black mustard, cudweed, cultivated barley, and ripgut grass as characteristic. Plummer's baccharis, also listed, was reidentified as Adriana goldenweed during review of the 1993 study.	4, 16
Uplands. Acreage is for the lagoon and vicinity.	26	Native upland communities include southern coastal foredune and bluff scrub, Diegan coastal sage scrub, southern mixed chaparral, southern willow scrub, and Torrey pine forest. Also mulefat and arrowweed scrub and nonnative grassland.	4

ANIMAL USE			Source
Birds	11 surveys of wetland habitats April 1992 - April 1993 found 143 species, including 15 sensitive and 9 invasive; 52% were water birds; breeding Belding's Savannah sparrows# identified, also 10 pairs of Ca. least tern+ nested unsuccessfully.		4, 14, 16
	1994 total of monthly censuses was 125 - 64 waterbirds, 61 upland; 14 special status species.
Fish	18 surveys March 1992 - May 1993 of all water habitats using beach seine, beam trawl, and enclosure found 24 species; composition and abundance varied seasonally and with condition of ocean inlet; topsmelt, small gobies and yellowfin goby* were		4
	dominant west of I-5, mosquitofish* and gobies dominated east of I-5; Ca. halibut and diamond turbot were among species frequently caught.
Benthic Invertebrates	Nov 1992-Apr 1993 42 taxa in intertidal stratum, Polychaetes (Capitella, Polydora, Streblospio), oligochaetes, small barrel bubble snails (Cylichnella), clams (Tagelus), phoronids, larval flies, biting/non-biting midges most common.		4
Insect	Feb 1993 flying insect data from surveys of salt marsh and 2 upland habitats listed flies as most abundant in all habitats; beetles, including Staphylinid burrows, leafhoppers and planthoppers, thrips, ants, bees and wasps also present.		4
Other Wildlife	April 1992 survey of beach, marsh west of I-5 and marsh and upland east of I-5 found 9 of 20 expected species of amphibians and reptiles, including the orange-throated whiptail+, and evidence of the San Diego horned lizard+; the northwestern pond turtle		4
	was described as known to occur in the river east of El Camino Real. May 1992 survey identified 9 species including coyote and Norway rat in the salt marsh; striped skunk, raccoon and long-tailed weasel in transition areas.
Special Status Species	San Diego horned lizard, orange-throated whiptail, common loon, brown pelican, white-faced ibis, osprey, no. harrier, sharp-shinned hawk, West snowy plover, long-billed curlew, Ca. gull, elegant tern, Ca. least tern, black skimmer,		4, 14
	tricolored blackbird, Belding's Savannah sparrow#, Ca. gnatcatcher.

OUTLOOK			Source
Enhancement Status	An enhancement plan was prepared in 1979 and during 1983-1984 a 70-acre tidal basin was excavated, Crest Cyn gully was repaired, and the mouth was opened. A conceptual plan for enhancement within the context of a regional		7, 16
	river parkway was prepared in 1989, and the lagoon is the intended site for a mitigation project that would involve restoration of 150 acres of tidal wetland and maintenance of the tidal inlet.
Watershed Management	In 1994 the San Dieguito River Park Joint Powers Authority prepared a concept plan for a regional open space park for 55 miles of the river corridor with the goal of preserving and restoring land to protect natural, cultural resources,		3, 2, 1
	and provide compatible recreation; 1/3 of the land within the planning area is publicly owned. The City of San Diego draft San Pasqual Valley Plan completed in 1994 is part of an effort to resolve issues regarding endangered species habitat,
	flood control, mining, agriculture, water quality in the valley.
Pressure	Structural constraints on the reach of tidal flow; establishment of exotic vegetation; flood control concerns; retention of freshwater flows and sand and gravel behind dams.		4, 9

SOURCES
1	City of San Diego. 1994. Draft San Pasqual Valley Plan.
	Analyzes land use issues and identifies goals and recommendations to guide land use decisions in the San Pasqual Valley. The plan area is a sparsely populated region of approximately 11,000 acres within the San Dieguito basin. The overall
	goal of the plan is to outline a process that provides for flood control, agriculture, circulation, recreation and sand mining while protecting biologically sensitive habitat and the rural character of the area. Based on existing information.
2	San Dieguito River Park Joint Powers Authority. 1994. San Dieguito River Park concept plan. 126 pp.
	Establishes the vision and goals for the future use of the San Dieguito River Valley. Describes the plan context and purposes, planning considerations, and park plan concepts (objectives). May be amended and updated periodically. Prepared to
	serve as policy document for the JPA.
3	Southern California Edison. 1994. Ownership maps prepared for San Onofore Nuclear Generating Station project.
4	MEC Analytical Systems, Inc. 1993. San Dieguito Lagoon restoration project biological baseline study, March 1992 - May 1993. Volume 1, 2nd edition. Draft Technical Memorandum. Prepared for Southern California Edison. 390 pp. Raw data in separate volume.
	This report provides baseline information on physical, chemical and biological conditions at San Dieguito lagoon, within the area generally below 10 ft NGVD. It describes methods and findings of a detailed monitoring program conducted between March 1992
	and May 1993 to characterize physiography, sediment characteristics, hydrological inputs, water quality, benthos, fish, vegetation, birds, amphibians, reptiles, mammals and insects of the site. The report also summarizes previous studies and
	compares conditions at San Dieguito with other lagoons in the region. Prepared as basis for design of tidal wetland restoration measures to be carried out as mitigation in the lower San Dieguito River Valley.
5	MEC Analytical Systems, Inc. 1993. San Dieguito Lagoon restoration project biological baseline study, March - August 1992. Draft Technical Memorandum. Prepared for Southern California Edison. 327 pp. and separately bound appendices.
	Summarizes the results of the first six months of the baseline studies, including a) short-term studies of responses of water quality, fish, birds, and endangered species to opening and closing of the mouth of the lagoon; b) long-term studies of responses
	of water quality, fish, birds, and endangered species to seasonal changes in environmental conditions in the lagoon resulting from freshwater runoff, tidal exchange, and insolation; and c) one-time surveys for
	vegetation, amphibians and reptiles, and mammals. A subsequent report is planned to cover a full year of studies. Prepared as basis for design of tidal wetland restoration measures to be carried out as mitigation in the lower San Dieguito River Valley.
6	MEC Analytical Systems, Inc. 1991. Ecological Descriptions and Evaluation of proposed enhancement/restoration for eight southern california wetlands. Final Report. Prepared for Southern California Edison. 300 pp. and appendices.
	This document describes the characteristics of eight wetland sites in Southern California and provides an assessment of their relative value as candidates for biological enhancement and restoration required as compensatory mitigation.
	The assessment is organized into four parts: historical acreage and present ecological condition; proposed enhancements and restorations; evaluations of proposed enhancements and restorations based on biology; and evaluations of proposed
	restorations and enhancements based on Coastal Commission objectives and standards. Appendix A describes each wetland site in detail. A variety of existing documents are incorporated into the document.
7	San Dieguito Lagoon and River Valley Committee (City of Del Mar), The Spurlock Office and James Massey Enterprises. 1989. Conceptual plan for the expanded San Dieguito Lagoon resource enhancement program. 31pp.
	Describes the San Dieguito Lagoon and proposes preliminary ideas for enhancement. Concepts for biologic and aesthetic enhancement and increased public benefit of lower San Dieguito River Valley between the ocean and El Camino Real
	are discussed. Plan elements include conservation and management, public use, interpretive programs, and regional circulation and access. No indication of original field work.
8	State Coastal Conservancy. 1989. The coastal wetlands of San Diego County. 64 pp.
	Public education booklet describing ecological concepts and dynamics of San Diego County salt marshes. Discussion includes watershed processes, littoral and tidal influences, habitat types, significance to migratory
	birds, and the effects of urban development. Profiles the history, current values and problems, protection efforts and public access opportunities at 13 wetland areas.
9	State Coastal Conservancy and the City of Del Mar. 1979. San Dieguito Lagoon resource enhancment program. 115 pp. and appendices.
	Report outlining a long-term plan for enhancement and restoration of the lagoon. Provides a brief history of the site, and characterizes existing habitat types, geology, plant and wildlife
	communities, soils, and hydrology based on existing information and field surveys.
10	Department of Fish and Game. 1976. The Natural Resources of San Dieguito & Batiquitos Lagoons. 110 pp.
	Comprehensive descriptions of San Dieguito and Batiquitos lagoons and their environs with recommendations for maintaining and enhancing existing resources. The document characterizes geologic and hydrologic conditions,
	vegetative, aquatic invertebrate, fish, bird, mammal, and reptile resources, and identifies problems with respect to maintaining resource health. Includes original vegetation, bird, mammal, fish and aquatic invertebrate surveys.
11	City of San Diego. 1994. Torrey Pines Community Plan Update and North City Local Coastal Program Land Use Plan Amendment. Environmental Impact Report. 63 pp. and Response to Comments.
	This report details the environmental setting and analyzes the potential environmental impacts of the Community Plan. The impact analysis focuses on traffic and circulation, air quality, biology, hydrology
	and water quality, visual quality, and cultural resources. No indication of original field work. Analysis based on information available to the City of San Diego.
12	City of Del Mar. 1988. Zoning Map
13	San Dieguito River Park Joint Powers Authority. Personal communication. Susan Carter, July 14, 1995.
14	San Diego Audubon Society. 1994. San Dieguito Bird Census for 1994. Charmian Ariotti Count Leader. Unpublished survey data.
	Summary of monthly species counts carried out by the San Diego Audubon Society at San Dieguito Lagoon. Includes field notes listing observers and their remarks.
15	Coastal Environments. 1995. Long-term probability of open inlet at San Dieguito Lagoon: Volume I Technical Report. 28 pp.
	Findings of a study undertaken to estimate the proportion of time that the mouth of San Dieguito Lagoon would be open over the next 30 years without mechanical intervention. The projection is based on a time series analysis of long-term
	historical observations of inlet status. Also included is a discussion of the relative importance of the processes that determine whether the inlet is open or closed. Prepared for the Southern California Edison Company.
16	California Coastal Commission, personal communication. Dan Reed, July 11, 1995. John Boland, July 13, 1995.
17	John Boland, California Coastal Commission. November 16, 1995 correspondence.
	Excerpts from an in-house history of San Dieguito Lagoon prepared in 1994 from aerial photography and literature search.
18	San Diego Regional Water Quality Control Board. 1994. Water quality control plan for the San Diego basin. Approximately 225 pp. and appendices.
	The plan designates beneficial uses and associated water quality objectives for inland surface waters, coastal waters, reservoirs and lakes and ground water in San Diego County. 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. Appendices contain summaries of regional growth forecasts and criteria for organic and inorganic constituents.
19	State Water Resources Control Board. 1994. List of impaired water bodies.
	Developed as part of the Water Quality Assessment of the State's major waterbodies. Separate lists are developed to rate waterbodies as Good, Intermediate, Impaired or Unknown Quality. Impaired waters are those not expected to attain or maintain
	water quality standards. The state list is a compilation of those developed by the nine regional boards. Lists of impaired water bodies are also known as 303(d) lists as they meet a requirement of section 303(d) of the federal Clean Water Act.
20	San Diego Regional Water Quality Control Board. 1996. Draft 303(d) list.
	A proposed list of waterbodies in the San Diego Basin that do not or are not expected to attain water quality standards after application of required technology-based controls. Specifies selected beneficial uses and criteria assessed,
	and the percentage of samples in which criteria were exceeded. It also identifies waterbodies for which previous assessments are no longer applicable.

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