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Floodplains Development is widespread on many floodplains of rivers and creeks throughout the West. Large parts of the alluvial valley areas of California are historic floodplains, low areas adjacent to waterways that flood during wet years, Urban areas developed in the floodplains because rivers were the main routes of commerce, In addition, floodplains often contain the best soils for agricultural crops because overflowing rivers leave behind layers of silt and topsoil. Floods in these vulnerable areas have caused billions of dollars in damage, Congress created the National Flood Insurance Program (NFIP) in 1968 to reduce the loss of life, damage to property and rising disaster relief costs in these high risk areas. This incentive-based, voluntary program is admin- istered by the Federal Emergency Management Agency (FEMA) and aims to end the expensive cycle of flooding and rebuilding, The program re- quires that new or replacement buildings in flood hazard areas be constructed to mitigate future flood damages, FEMA insists on assurances that local upstream flood repair mea- sures and devel- opment in the floodplains will not exacerbate flooding in other communities. It guides future development away from flood prone areas and transfers the costs of flood losses from American taxpayers to floodplain property owners. Local officials are required to regulate development in these designated floodplain areas fhrough the adoption of a floodplain management ordinances, which meet the minimum NFIP regulations. Ordinance requirements can include elevating the lowest floor of new homes at or above the 100-year flood elevation to prohibiting new buildings, Aerial view of levees and housing developme11l along the Sacramento River: These homes (ire protected by the coordinated efforts of man)' local, state and federal flood control agencies. 10 Participating communities identified with special flood areas are required to comply with certain development standards to qualify for federally subsidized flood insurance. (Property owners in these participating communities qualify for flood insurance whether or not their structure is in a floodplain, Federally subsidized flood insurance is available for older structures built prior fo a flood- plain designation, If new development does not comply with NFIP standards, the property owner pays higher flood insurance premiums,) Many people, however, do not purchase flood insurance and assume they will be protected by the federal government. Following the 1997 floods, FEMA reported only about 260,200 NFIP policy holders in California, a comparatively small amount given the state's population and number of flood-risk areas. The flood insurance program was reported to be more than $9 million in debt. FEMA works with state and local governments to designate Special Flood Hazard Areas, At a minimum, these are areas determined to be within the 100-year flood boundary of a waterway, Local agencies may exceed these minimum standards and designate larger areas. Flood maps often are revised as new data are acquired and new areas are mapped, but not without considerable controversy. In addition, some contend that too much reliance is placed on the floodplain maps Under pressure from FEMA, Sonoma County imposed stringent rebuilding restrictions in the disaster zone following the 1986 floods, Sonoma revised their ordinance to require that when flood damage costs exceeded 50 percent of market value of the structure, owners were required to elevate the building 1 foot above 100.year flood levels, These restrictions were very costly, but those who modified their homes weathered the 1995 floods better than their neighbors, Flood levels in 1995 were nearly as high as in 1986, and several hundred people were evacuated from Sonoma and Napa counties. Parts of Sacramento were subjected to revised maps following the 1986 floods, Corps engineers reas- sessed the adequacy of the local levee system and estimated that a 100-year flood could cause $15 billion in damage and cost as many as 100 lives in the American River floodplain, The city of Sacra. mento and the adjoining community, including nearly 400,000 residents, were included in the revised floodplain map, The Natomas area at the junction of Interstates 5 and 80, which consists of 86 square miles targeted for new development, was included in the revised FEMA floodplain, It had existed for eons as a floodplain when it was part of the American River basin, before any levees were built, Extensive levee repair and upgrades were carried out along the Sacramento River system to increase protection to a 1 OO-year level. Reoperation of Folsom Dam and reservoir to include more interim flood control storage