Monitoring Southern California's Coastal Waters (1990) / Chapter Skim
Currently Skimming:
1 The Southern California Bight
1 The Southern California Bight
Pages 1-15
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From page 1... ...
Chapter 2 will describe in greater detail the sources and types of habitat change and pollutant loadings to the marine environment that stem from human activities in the bight. PHYSICAL SETTING The Southern California Bight is bounded on the north, east, and southeast by a long cume of the North American coastline extending from Point Conception in Santa Barbara County, southeast 357 mi to Cabo Colnett, Baja California in Mexico (Figure 1-1~.
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The most important embayments of the mainland shelf are Santa Monica Bay and San Pedro Bay (separated from each other by the prominent and steeply sloping Palos Verdes Peninsula and shelf) , San Diego Bay, and Todos Santos Bay in Baja California.
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There are as many as 20 raised marine terraces on land that are an extension of the 5 submerged terraces that lie at depths to 289 ft along the mainland shelf (Emery, 1960~. The drainage basin is bordered on the north by transverse (east-west ranges extending from Point Conception eastward along the Santa Monica,
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From north to south, the major rivers in the drainage basin are the Santa Clara, Los Angeles, San Gabriel, Santa Ana, San Luis Rey, San Diego, and Tijuana rivers (Figure 1-2~. Much of the length of the Los Angeles and San Gabriel river beds and other major drainages are now lined with concrete.
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there is a northwestward current How of 25 cm/s or less inshore of the California Current (Figure 1-3~. This water is of equatorial Pacific origin and has a higher temperature, salinity, and phosphate concentration and a lower oxygen concentration than the deep water in the California Current located at the same depth but farther offshore (Jones, 1971~.
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These are the El Nino events, which occur several times per decade (e.g., 1976, 1979, 1982-1984, 1986-1987) and are characterized by warm water, a deeper surface-mixed layer, elevated sea levels, increased abundance of southern planktonic and pelagic organisms, alterations of benthic community structure, and degeneration of coastal kelp beds (Jackson, 1986~.
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8 a ~ ~0\ ~ ~ -~ Cal Cal Cal ~Cal Cal 0 __ e .
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This includes primary, secondary, and tertiary treated sewage discharged directly to the ocean from coastal treatment plants and tertiary treated sewage discharged from inland treatment plants to Southern California rivers and streams. This pattern of freshwater input to coastal waters is quite different from that in much of the rest of the coastal United States, where riverine and stormwater flow far exceeds wastewater flow.
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From page 10... ...
SOURCE: Califomia Department of Water Resources, 1987; Los Angeles Department of Water and Power, 1985-1986 Annual Report; State Water Contractors, Bay-Delta Hearings, June 1987, SWC Exhibit Numbers 3, 6, 13, 17, 76. and offshore oil reserves, commercially or recreationally valuable fish and shellfish stocks, wildlife breeding and overwintering areas, kelp beds, beach and water recreation areas, and a climate tempered by the special oceanographic processes reviewed above.
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These storms probably are the most important factor influencing the condition and areal extent of kelp beds, but human activities such as kelp harvests, boat traffic, and possibly wastewater discharges at Palos Verdes and Point Loma have also affected local giant kelp beds. LAND USE AND ECONOMIC ACTIVITY A combined U.S.-Mexico population of about 15 million people lives in, works in, and enjoys the coastal climate and resources in the drainage basin of the Southern California Bighte The population in this area has increased steadily since the 1890s.
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From page 12... ...
. Secondary or tertiary treated sewage from inland treatment plants makes up much of the permanent flow of the Los Angeles, San Gabriel, Rio Hondo, and Santa Clara rivers in Los Angeles and Ventura counties.
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The region's 30,000 to 40,000 pleasure boats are concentrated primarily in Marina del Rey on Santa Monica Bay, in the new Los Angeles City Cabrillo Marina, in Alamitos Bay, Long Beach Marina, Huntington Harbor, Balboa-Newport harbors, northern San Diego Bay, and Mission Bay; and secondarily in marinas at Oceanside and Dana Point, and in Oxnard, Ventura, and Santa Barbara. Because pleasure boats are sources of fuel leaks and toxins from antifouling paints, they constitute a potential environmental problem that has not yet been quantified.
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The least developed areas of the bight include the northwesternmost 37-mi stretch of coast between Point Conception and Santa Barbara, the 12-mi coastline of Camp Pendleton in northern San Diego County, the central San Diego County coastline, the Channel Islands, and the Baja California coast south of Ados Santos Bay, near Ensenada. In summary, there is little coastal space that has not been subject to construction, mineral extraction, or other forms of resource utilization.
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From page 15... ...
15 Finally, as a result of Southern California's large population and attendant intense economic and recreational activity, there is little coastal space that has not been subject to construction, mineral extraction, or other forms of resource utilization. This activity has resulted in extensive habitat change and lame and wried inputs of contaminant to the bight.
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