The Flood Crisis in California’s Central Valley

California flood officials watched with dismay the destruction and despair created by Hurricane
Katrina, knowing that a myriad of such tragedies could easily come to California. While California does not generally suffer hurricanes, it receives significant precipitation and runoff from
warm winter storms. In fact, the odds of a catastrophic flood were higher in California because the levels of protection provided by most of its levees are much lower than those associated with the levees that protected New Orleans.
Last year, California’s Department of Water Resources (CDWR) released “Flood Warnings: Responding to the Flood Crisis in California.” This white paper was mandated by the California
Legislature to document challenges associated with a deteriorating levee system in the state’s Central Valley and outline possible solutions. Among the findings was that California’s Central
Valley flood control system is not only deteriorating, but in many places is literally washing away. At the same time, California’s growing population is pushing new housing developments and job centers into the floodplains of the Central Valley. Flood control funding cuts at many levels of government combined with increasing liabilities have created a ticking time bomb for
flood management in California. The Early Days Rimmed on the east by the Sierra Nevada and on the west by the Coast Range, California’s Central Valley is basically a large bowl collecting most of the state’s rainfall. Prior to the development of the West, the valley periodically would become a huge inland sea when valley flood waters overflowed their banks and spread across the floodplains. As farmers began moving into the Central Valley floodplains in the early to mid-1800s, they constructed small dikes or levees to provide some protection against flooding and reclaim the land for agricultural development. Soon, communities such as Sacramento, Marysville, and Stockton sprang up along the rivers. Limited flood control efforts failed to provide much protection and many communities and surrounding lands were repeatedly
flooded. Mining activity in the mountains worsened the situation by filling many river channels with so much silt and sand that navigation and flood carrying capacity were severely impacted.
In the late 1800s a system of new levees, weirs, and bypass channels was proposed. The federal government agreed in the early 1900s to lead efforts to construct flood control projects in the Central Valley, and a California State Reclamation Board was formed as the local sponsor.
The board provided land, easements, rights-of-way and, in some cases, a local cost share. It also agreed to accept ownership of the projects completed by the U.S. Army Corps of Engineers, maintain the system, and hold the federal government harmless. Much of the levee system was later turned over to local reclamation districts to maintain.

Read Full article http://swhydro.arizona.edu/archive/V5_N2/feature3.pdf