Since settlement of California's Central Valley in the mid-1800's, aquatic habitat quantity and quality has declined dramatically, so much so that many aquatic species, including some anadromous fish, are on the verge of extinction. Historically, many factors contributed to this decline in aquatic habitats including hydraulic mining; water quality degradation; introduction of exotic fish species; construction of dams, dikes and levees; water diversions; and river and stream canalization.

The following table provides estimates of loss for native aquatic habitats in California's Central Valley and Central Coastal areas.

Putah Creek near Davis

Wetlands

Central Valley and Central Coast areas from sea level to areas above 5,900 feet where soils are saturated or at least periodically flooded.

Over 90% loss from historic levels with an estimated 400,000 acre loss since the 1940's within areas receiving water deliveries from the Federal and State water projects.

Wetland dependent species include waterfowl, shorebirds, and a host of mammals like the raccoon.

Representative special-status species include the giant garter snake, California red-legged frog, tricolored blackbird, and the salt marsh harvest mouse.

See our Amphibians & Reptiles page.

Vernal Pools

Central Valley-wide in areas with an impervious substrate insuring a perchable water table. Typically located in grassland areas.

Due to agricultural and development practices Central Valley-wide, several associated plant and invertebrate species have been federally listed, including several species of fairy shrimps, the vernal pool tadpole shrimp, and Sacramento Orcutt grass.

See our vernal pool page

Other Aquatic Habitats

Central Valley and Central Coast areas from sea level to the top of watersheds.

By actions including the construction and operation of the Federal and State water projects, the natural hydrology of the Central Valley and Central Coast areas has been profoundly changed. These changes have resulted in the alteration of estuarine habitat hydrology and productivity.

Impacts to riverine habitats include the inundation and adverse modification of hundreds of river miles, and the loss of access for many species to thousands of river miles.

Aquatic habitat-dependant species include resident fishes, the beaver, river otter, and American dipper. Special-status species inhabiting these areas include the bald eagle, Shasta crayfish and delta smelt. 

See our riparian ecosystems page