Prior to construction of the levees the Sacramento River would rise up out of its banks during the wet winter months to form and inland sea across the valley floor. Many miners who had previously been farmers, recognized the potential of the fertile soils that covered the Sacramento Valley and set out to reclaim the swamp lands from overflow.
The first levees were built by individual landowners using substandard materials. The Sacramento Flood Control Project was authorized by Congress in 1917 and completed by the Army Corps of Engineers in 1960. Today the flood control districts act as the local maintaining agency to perform maintenance on the levees. All of the levees constructed by RD 108 have now become part of the federally sponsored Sacramento River Flood Control Project. There are over 1,600 miles of State/Federal Project levees.
The Sacramento Flood Control System was never designed to hold the maximum carrying capacity of the River. The levees are not high enough or far enough apart to withstand maximum flows. Instead the flood control system relies on a variety of management tools such as reservoirs, bypasses, and weirs to provide relief for overflows. Over the years the carrying capacity of the River has changed. Riparian habitat has been restored and promoted along the river banks. Woody debris and other vegetation builds up in the river channels creating sand bars and islands in the middle of the floodway.
Excessive rains do not always preface flooding. The numerous miles of levees create a challenge for maintenance and upkeep, combined with the age of the levees. Deteriorating levees have become a challenge for the State to ensure flood protection.