Agua Hedionda Lagoon

GENERAL			Source
Site	Agua Hedionda Lagoon
Map	San Luis Rey 7.5' USGS Quadrangle
Location	The lagoon is located within the City of Carlsbad off Carlsbad Boulevard.
Contacts	San Diego Gas and Electric, 619-696-2732
Approximate Wetland Habitats Acreage	330		11
Approximate Historic Acreage	230 acre marsh prior to signficant dredging in 1954.		1

Ownership	Owner	Acres
	San Diego Gas and Electric (leases to YMCA, the City of Carlsbad and private businesses)	286	2

LAND USE			Source
Land Use Designation	The area is designated open space in both the general plan and zoning ordinance for the City of Carlsbad.		8, 9
Onsite Use	Carlsbad Blvd. (Highway 101), I-5, and the Santa Fe Railroad divide the lagoon into three basins (outer, middle and inner lagoons). A San Diego Gas and Electric (SDG&E) power plant sited along the outer and middle basins takes its cooling water from the lagoon. SDG&E also leases land for various uses including mariculture of mussels, oysters, and sea bass, and a youth camp, private marina and public boat launch. The inner lagoon is used for active recreational water sports.		1, 2
Historic Use	San Diego Gas and Electric constructed the Encina power plant and a tidal basin to provide its cooling water in the 1950's.		1, 6
Adjacent Use	The southern shore of the outer and middle lagoons is occupied by a power plant and support facilitities. Agricultural activities occur to the south and residential development is located to the north. The southern shore of the inner lagoon is undeveloped with adjacent land used for agriculture. Carlsbad Blvd. and the ocean are located to the west of the lagoon. The area to the east of the inner lagoon is undeveloped. Carlsbad State Beach is located to the west.		1
Historic Adjacent Use	Agriculture		1

HYDROLOGY			Source
Tidal Influence	The original slough was only occasionally open to the sea. An inlet channel of rip rap jetties, which keeps the mouth permanently open, was built in 1954. The power plant draws water from the lagoon and discharges the cooling water into a second discharge channel that empties directly into the ocean. The three basins of the lagoon are connected via openings under I-5 and the railroad. However, the berms for these crossings limit the reach of tidal action.		1, 2
Watershed Area	29 square miles		1

Tributaries and Flow	Tributary	Flow	Source
	Agua Hedionda Creek	Not specified.	1
	Buena Creek	Not specified.	1
Dams	None specified.
Other Sources	Freshwater also enters the lagoon from 23 storm drains, urban runoff along the northern shore, and agricultural runoff along the southern shore.		1

WATER QUALITY			Source
General	Included in 1996 draft list of impaired water bodies; selected standards exceeded for sediment and coliform bacteria. Beneficial uses are ind, rec1, rec2, comm, est, wild, rare, mar, aqua, migr and shell.		3, 4
Dissolved Oxygen (DO)	1994, 1995- Data were collected at nine stations covering all basins in July, 1994 and April, 1995. Bottom DO concentrations in July ranged 7.5 - 12.7 mg/l, the range for April was 8.2 - 18.4 mg/l. Time of samples was not indicated.		1
	Bottom temperatures ranged 20.83 - 24.73 C in July and 14.8 - 16.4 C in April.
Water Salinity	1994, 1995 - Data were collected at nine stations covering all basins in July, 1994 and April, 1995. Salinity was 32 ppt throughout the water column in July; bottom salinities ranged 30 - 32 ppt in April.		1
Sediment	An estimated 120,000 cubic yards of beach sand enters the outer lagoon due to the process of longshore drift; this is dredged periodically. Agua Hedionda Creek also contributes sediment; by 1993, a settling basin in the inner lagoon excavated to -17 msl in 1954, had filled and a delta extending 1000 ft into the eastern end of the lagoon had formed.		6, 10

Soil			Source
Soil	Soils at the lagoon are Marina loamy coarse sand on the marine terrace, Las Flores loamy fine sand at the inner lagoon and Salinas clay loam on the tidal flats.		6

Habitat	Acres	Vegetation
Open water	253	Not specified	11
Eelgrass Occurred in all basins.	Not specified	1994 - eelgrass	1
Estuarine flats	49	Not specified	1
Salt marsh Patchy along the shore of the middle and inner lagoons.	14	1994 - Common salt marsh species included pickleweed, saltgrass, fleshy jaumea, and alkali heath.	Ac. 11 Plants 1
Brackish/ freshwater marsh	3	1994 - Cattail, bulrush and spiny rush	Ac. 11 Plants 1
Riparian	11	Not specified	11
Upland	61	1993 - coastal sage scrub/chaparral, ruderal, and nonvegetated disturbed.	11

ANIMAL USE			Source
Birds	Monthly surveys Aug 1994 - June 1995 found 81 species; 61 water associated, 20 upland. 12 sensitive wetland species observed, including nesting Belding's Savannah sparrows#.		1
Fish	July 1994, April 1995 beam, otter trawl and beach seines caught 29 species. Samples were collected at 21 stations throughout the lagoon. Silversides, gobies and diamond turbot were most abundant.		1
Benthic Invertebrates	July 1994, April 1995 -143 taxa were collected by beam trawls and 76 taxa were collected by hand cores. Samples were collected at 26 stations throughout the lagoon. Cockle, mussel, crustaceans, amphipods, and isopods were the most abundant taxa caught by the beam trawls. Nematodes, phoronids, oligochaetes, and polychaete worms were the most abundant infaunal invertebrate species collected by cores. One speckled scallop was collected in the middle lagoon.		1
Insect	Not specified.
Other Wildlife	1976 - The California slender salamander, western spadefood frog and western toad were expected to be present at the lagoon, but were not observed. The Pacific tree frog, side-blotched lizard and western aquatic garter snake were identified at the lagoon. Ten mammal species were identified at the lagoon and upland areas, including coyote, fox, bobcat and rabbits.		6
Special Status Species	1994-95 - Belding's Savannah sparrow# nests at the lagoon; California least tern+, western snowy plover+, brown pelican+, white-faced ibis+, California gull+, osprey+, cooper's hawk+, long billed curlew+, loggerhead shrike+, northern harrier+, and black skimmer+.		1

OUTLOOK			Source
Enhancement Status	A mitigation project involving restoration of several wetland habitats was undertaken in 1985 and considered unsuccessful. San Diego Gas and Electric expects to implement a dredging project in the future which might involve planting of eelgrass.		2, 5
Watershed Management	The City of Carlsbad has a Master Drainage and Stormwater Quality Management Plan and implements an erosion control ordinance for all construction projects. There is no formal program to address sediment from agricultural activities.		7
Pressure	Sedimentation from agriculture and urban development in the watershed, pressure on habitats and wildlife from active recreation and adjacent development, and impacts to water circulation from the power plant.		1

SOURCES
1	MEC Analytical Systems Inc. 1995. 1994 and 1995 field survey report of the ecological resources of Agua Hedionda Lagoon. 47 pp., plus appendices.
	This report summarizes the results of field surveys conducted between April 1994 and June 1995 at Agua Hedionda Lagoon. The surveys collected original field data on eelgrass, salt marsh, birds, fish, and benthic invertebrates. Data were also collected for water quality. The surveys were designed to provide adequate environmental information to support agency review of a dredging project. The survey designs and methods were developed in consultation with the DFG, NMFS, COE and FWS.
2	Mark Chomyn. San Diego Gas and Electric. Personal communications, December 3, 1995 and February 13, 1996.
3	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.
4	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.
5	Josselyn, Michael, Joy Zedler, and Theodore Griswold.1990. Wetland mitigation along the Pacific coast of the United States. Pages 3-35in Jon Kusler and Mary Kentula, eds. Wetland creation and restoration-the status of the science.
	This article evaluates the effectiveness of wetland mitigation practices as applied to wetlands along the Pacific coast. It also proposes critical elements for successful mitigation according to wetland type and identifies research needs.
	The report includes an introduction to the basic types of wetlands that occur in the region, and a review of the types of projects permitted as well as previous evaluation efforts and methods. Appendices contain an annotated bibliography and case studies of 7 mitigation projectsincluding those carried out at Agua Hedionda Lagoon and Sweetwater Marsh.
6	California Department of Fish and Game. 1976. The Natural Resources of Agua Hedionda Lagoon. 107 pp., plus appendices.
	This report summarizes the Agua Hedionda Lagoon and its environs and resources. Physical features, history, land use, ecology, and resource use are summarized. It concludes with a discussion on problems and conflicts of use. Appendices include species
	lists for plants, birds, mammals, amphibians and reptiles, and fish expected to occur at the lagoon.
7	Steve Janz, City of Carlsbad. Personal communication, December 13, 1995.
8	City of Carlsbad. 1994. General Plan Land Use Map.
9	City of Carlsbad. 1995. Zoning Ordinance Map.
10	City of Carlsbad and U.S. Army Corps of Engineers. Batiquitos Lagoon Enhancement Project Final EIR/EIS Volume III. 1990.
	Technical appendices from a multi-volume EIR/EIS for the Batiquitos Lagoon Enhancement Project. Appendix H. discusses two studies analyzing the effects of the Agua Hedionda Lagoon inlet and discharge channels on littoral processes.
	The results are considered in light of potential design considerations for the Batiquitos Lagoon Enhancement Project. Studies are based on a combination of existing and field data.
11	MEC. 1993. San Dieguito Lagoon restoration project regional coastal lagoon resources summary. 56 pp and appendix.
	This report provides a summary of habitat types, fish, bird and benthic invertebrate populations at 16 coastal wetlands south of Anaheim Bay. It is primarily a synopsis of existing information; sources used in identifying and quantifying habitat types include aerial photographs taken in early 1993. Discusses restoration of habitats at San Dieguito Lagoon given present and historic conditions of other coastal wetlands in the region. This report was prepared as part of the San Dieguito Restoration Project undertaken by Southern California Edison to mitigate for damage to coastal marine resources from the operation of the San Onofore Nuclear Generating Station.
12	Zedler, Joy B. 1996. Coastal mitigation in Southern California: the need for a regional restoration strategy. Pages 84 - 93 in Ecological Applications, 6(1), 1996.
	The author asserts the need for a regional strategy for restoring and enhancing coastal wetlands in southern California, and outlines a process for its development. The article provides an overview of the current state of wetlands in the region and identifies proposed enhancement and restoration activities. It also describes and evaluates past mitigation and restoration efforts at Agua Hedionda Lagoon, Batiquitos Lagoon, and Sweetwater Marsh.

Webmaster: wetlands@resources.ca.gov