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About the Delta

What is the Sacramento-San Joaquin Delta? Where is it located?

The Sacramento-San Joaquin Delta, a land of stunning open spaces, cut by five major rivers, creeks, levees, bridges, and sloughs is both a natural and man-made place. It is a maze of finger-like waterways that spread throughout some of California's most prime farmland and natural habitat areas. While it extends into five counties, Solano, Yolo, Contra Costa, Sacramento, and San Joaquin, the majority of its lands and waters fall within Sacramento and San Joaquin counties.

Prior to reclamation, runoff from the Sacramento and San Joaquin rivers frequently flooded open Delta wetlands. Beginning with reclamation for farming in the late 1800s, the Sacramento-San Joaquin Delta was then divided into tracts (islands), as farmers began building levees that protected the larger islands from flooding. The 1100 miles of levees that were built over time not only give the Delta its present shape, but forever changed the environment of the area. Due to subsidence, the oxidization, compacting, and erosion of soil, most of the Delta's islands are now below sea level and are permanently dependent on well-maintained levees for sustainability.

The Sacramento-San Joaquin Delta is also the largest Pacific Coast estuary of both North and South America, the endpoint for about half of the state's runoff waters, the primary source of California's fresh water supply, and home to numerous fish and bird species, in addition to over 500,000 people. Fish, such as the Chinook salmon and the Delta smelt, are dependent on Delta habitat for survival.

In addition to providing habitat, the Sacramento-San Joaquin Delta contains more than 738,000 acres of land, used primarily for farming. Within its primary zone, defined by the Delta Protection Act of 1992, more than 60 islands make up the 500,000 acres which cannot be developed. In the Sacramento-San Joaquin Delta's secondary zone, defined as that part of the Delta where development can occur, a number of growing urban areas and communities such as Stockton, Lathrop, Tracy, Oakley, and West Sacramento depend on secure levees for protection against flooding.

Besides protecting agricultural and urban communities, as well as natural habitat, levees throughout the Sacramento-San Joaquin Delta protect power lines, highways, oil and gas pipelines, and deepwater shipping channels. Thus, revitalizing the Sacramento-San Joaquin Delta is essential to California's overall environmental and economic health.