Millions of migrant and wintering waterfowl once used Suisun Marsh. Market hunting in the late 1800s suggests the size of estuary waterfowl populations where more than 182,000 green-winged teal were sold in San Francisco markets in the 1895-96 season (Grinnell et al. 1918). Estimates of wintering pintail populations in the recent past, including the Delta, vary from 200,000 to 1.4 million (Michny 1979). San Francisco and San Pablo Bays made up one of the largest contiguous tidal marsh systems on the Pacific Coast and included over 545,000 acres of tidal wetlands. The hydraulic mining in the Sierra-Nevada foothills, conversion of tidelands to agriculture in the late 1800s and early 1900s, and urban and industrial expansion have reduced the quality of this system (Nichols et al. 1986). Urban expansion has created large residential developments within and adjacent to wetland areas; industrial, military, and commercial developments; over 320 marinas; solid waste landfills; and substantial disturbance of wildlife. Critical coastal wetland habitats still exist in southern California and include, Morro Bay, Bolsa Chica, and San Diego Bay, however, urban encroachment is severe.
Another crucial factor related to conservation of water birds and aquatic habitat in the Central Valley is that of water itself. Agriculture accounts for 80% of water use, and projected demographic changes will result in dramatically increased tensions among agriculture, urban development and conservation interests. Even in an above-average water year like 1998-99, farmers in the San Joaquin Valley did not fully receive adequate water supplies. Congressional actions, such as 1992 passage of the Central Valley Project Improvement Act, have helped assure adequate water supplies for wildlife conservation in some areas (such as federal and state refuges), yet much remains to be done to secure adequate supplies of water quantities of suitable quality for wetlands conservation (especially private lands).
An additional factor related to water in the west is that of threatened and endangered anadromous fish. Almost all rivers and streams in northern California have large and small dams that halt successful salmon and steelhead spawning cycles. Alterations of streamside habitat and water availability at important times in the year further exacerbate the problems. Water diversions from streams and rivers for agricultural or wildlife conservation use can result in entrapment of fish onto upland areas, further compromising their population status. If solutions to such fish issues cannot be found, direct conflict in floodplain management strategies would certainly develop.