A water quality management plan is being prepared for Contra Costa County. Tidal waters of the San Francisco Bay estuary extending northward from Richmond to Carquinez Straits and eastward to Antioch and the Western Delta are of major concern. The study area, shown in Figure 1, is bordered by extensive industrial development and the waters offshore form the migratory route of salmon, striped bass and steelhead and the home of a diverse aquatic community including the sensitive neomysis shrimp, a favored food of young striped bass. Recreational uses and fish and wildlife habitat are high on the list of beneficial water uses to protect. One of the water quality factors found to be most critical in the design of water quality management alternatives was biostimulation. Any water quality factor that promotes the growth of aquatic plants can be considered as a biostimulant. Such factors include major nutrients such as phosphorus, nitrogen, and carbon as well as trace elements and vitamins and environmental factors such as light, temperature, and substrate. The major nutrients have been measured in numerous extensive studies of the northern portion of the bay during the past ten years, including University of California, USBR monitoring and special studies by the California Department of Fish and Game, Department of Water Resources and federal agencies such as the Public Health Service, Federal Water Quality Office, and the Geological Survey. These investigations provide much data on existing concentrations of total nitrogen and total phosphorus and seasonal variations in the nutrient forms, environmental factors, and patterns of algal growth in the bay and delta.