Coastal Services Center

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Case Study

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The bay is home to a wide variety of flora and fauna, including a number of threatened and endangered species. Although a great deal of commercial and recreational fishing takes place there, in recent years the stocks have become depleted and local landings are fewer and fewer.

Studies completed in the 1970s documented that increases in agricultural development, population growth, and sewage treatment plant discharges were causing the Bay to become nutrient enriched. Nitrogen and phosphorus are the two primary nutrients required to sustain aquatic biological productivity. Although phosphorus is the limiting nutrient in most freshwater systems, nitrogen is the limiting nutrient in most coastal estuarine and marine waters.

Bay water quality monitoring data confirm the significant progress made in reducing phosphorus from nonpoint sources and municipal point sources, but indicate that further progress is needed toward reducing nitrogen loadings.

Nonpoint sources of nutrients contribute about 60 percent of the nitrogen that reaches the Bay. The largest single source is agricultural runoff. Nitrogen loading results from application of chemical fertilizers, livestock manure, and sewage sludge on fields as well as from animal wastes that run off pastures and feedlots. Other nitrogen sources include atmospheric deposition to tidal surface waters, adjacent ocean waters, and the watershed, as well as runoff from urban and suburban lawns, roadways, and other developed areas to creeks and tributary rivers.