Delta Levees

What is a levee?
A barrier constructed to contain the flow of water or to keep out the river waters. 

Levee System contains the rivers
The Sacramento-San Joaquin Delta includes approximately 60 islands protected by more than 1,100 miles of levees that were built about 150 years ago to prevent flooding of farm lands. 

Today, the levees protect not only farms but also hundreds of thousands of people who live and work in Delta communities. State highways, railroad lines, water supply pipelines that serve much of the San Francisco Bay Area, energy transmission lines and petroleum pipelines also cross the Delta and rely on the continued stability of the levees. 

The force of the river and soil erosion contribute to levee deterioration. In addition, peat soils have subsided, gradually lowering the elevations of Delta islands. 

In the last 100 years there have been over 160 levee failures. This not only threatens life and property, but can also jeopardize the freshwater supply by allowing seawater from San Francisco Bay to enter areas that are critical to the distribution of freshwater. 

Photo courtesy of the California Department of Water Resources