California's Water: Sacramento-San Joaquin River Delta

Just a few miles south of Sacramento, two of California’s major rivers converge to form one of the most important features of California’s water system – the Sacramento-San Joaquin River Delta. More than 23 million Californians and millions of acres of farmland rely on the Delta for all or part of their water supply, and countless species depend on it for their habitat.

But for all its importance, few people know anything about the Delta. This segment of “California’s Water” focuses on the Delta and the aging levees that protect farmland, communities and critical infrastructure. The segment takes viewers on a boat tour of the Delta for a close look at this unique and vulnerable landscape, a discussion of its history and what it all means to California. Background on the Issue

Covering more than 700 square miles, the Delta is a patchwork of nearly 60 islands and tracts surrounded by natural and man-made channels and sloughs. It is a popular destination for boaters and other recreationists, and home to more than 750 distinct species of plants and wildlife. Salmon, striped bass and other key species such as Delta smelt depend on the Delta and its many marshes and waterways for their food and habitat.

Since about two-thirds of the islands and tracts are below sea level, the Delta relies on a maze of levees to protect land and key infrastructure from floods and daily high tides. In all, there are more than 1,100 miles of levees in the Delta, including many built more than a century ago to protect farmland. Were it not for these levees, the Delta would be a 740,000-acre brackish inland sea.

Today, the Delta’s aging and increasingly fragile levee system is being asked to protect much more than farmland. Three state highways, a railroad, natural gas and electric transmission facilities, and aqueducts serving water to parts of the Bay Area also are depend on Delta levees. In addition, more 400,000 people live in Delta towns and communities, some of which rank among the fastest growing areas in California.

The Delta is also the single most important link in California’s water supply system. Two of the state’s biggest water projects – the State Water Project (SWP) and the federal Central Valley Project (CVP) – depend on Delta waterways to convey water from Northern California rivers to pumping facilities in the southern Delta. Delta levees play a critical role in preventing salty water from San Francisco Bay from intruding into critical parts of the Delta and contaminating the fresh water that supplies communities and farms.