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Flood Management I The ri\'ers and streams ,hat bring prosperity to Ca/{fomia also can bring deaTh and destruction ~\'hell they bllrst from their hanks. 14 The rivers and streams that are the lifeline of California also can be tremendously destructive forces when they burst from their banks. Inundation of developed floodplains are a particular problem. Hydraulic mining practices during the Gold Rush era clogged the rivers with sediment, raised the river beds, and interfered with navigation and farming. In 1862. Sacramento was inundated by flood waters. in some areas the water was more than 20 feet deep. In response, landowners, merchants, and farmers joined forces to protest the practice of hydraulic mining. In 1884, it was prohibited by the federal court. The first plan to control seasonal flood- ing of the Sacramento Valley was tormed by State EngineerWilliam Hammond Hall in 1880. Once called the "Nile of the West," the Sacramento River yields about 35 percent of the state's water supply. In its natural state, the river periodically overflowed its banks during heavy winter rains and spring snowmelt. The need for flood control was highlighfed by devas- tating flooding between 1902 and 1909. In 1917 a Sacramento Flood Control Project was authorized consisting of a system of levees, overflow weirs, pumping plants and bypass channels. In times of high flows, the bypasses carry many times the amount of water left in the Sacramento River. Relieved from the threat ot 1I00ds. the area experienced an agricultural renaissance. Today the Central Valley has a 1I00d protection network that includes 23 reservoirs with flood de- tention space and more than 1.760 miles of feder- ally designated levees. overflow weirs and channels. In addition, a series of dams were built on the west- ern slope of the Sierra Nevada for both flood control and water supply. These include Shasta Dam on the Sacramento River, Oroville Dam on the Feather River and Folsom Dam on the American River. The flood management system has been sorely tested over the years - most recently by the 1997 New Year's flood. The January deluge, which was the second most devastating flood to hit this century. killed nine people, forced the evacuation ot 120.000 people, and caused nearly $2 billion in damage. The flood's destruction raised many questions - from technical to philosophical - about the limitations of floodplain management and the hazards of flood- plain development. Flood conditions in 1986, 1995 and 1997 prompted the Sacramento region to improve its existing flood control system. The long proposed Auburn Dam, on the American River above Folsom Dam, remains a controversial and unfinished leature ot the CVP. Though originally designed as a multi-purpose project, the focus in recent years has been on a flood- control only project at the Auburn site. Work on the dam was halted in 1977 following an earthquake which raised questions about the dam's satety and attempts to get the project completed have failed. In 2000. the Bureau began an EIRlEIS for filling in the by-pass tunnel to divert the river around the dam site, restoring the original river channel, and replac- ing the Placer County Water Agency pumps moved when dam construction began. Cost estimates for the proposed restoration hover around the 529 million mark to be cost-shared by state and federal entities. The mitigation plan is opposed by some who feel its implementation would signal an end to the Auburn Dam. In the state's more arid southern California region, flash floods prompted formation ot a flood control system in Los Angeles in 1915. It was the first flood control district. To protect against flash flood dangers, one of the largest and most intricate flood control systems in the world was constructed. The network is operated by the Los Angeles County Department of Public Works in coordination with the Corps. It includes 15 flood control and water conservation dams, 450 miles of open flood control channels, and 2,500 miles of underground storm drains. Flood control involves many diflerent local. state and federal agencies and their management philosophies change with the political and economic times. There is growing concern over the costs of providing disaster relief to property repeatedly damaged by floods. Traditional flood control strategies also have been aflected by the massive 1993 Mississippi River flooding. The concept of floodplain management came to the forefront and interest was renewed following the 1997 New Year's flood. Floodplain management includes giving constricted rivers more breathing room by setting back levees. reducing floodplain development and giving equal weight to environmental and economic factors in making management decisions. Complicating flood control practices and manage- ment are the often contlicfing water supply practices and needs. Flood control managers must keep enough reservoir storage space available to manage floods during heavy precipitation but water suppliers focus on storing enough water to protect against drought.