Experts say floods are likely, plan to live with them Chico Enterprise-Record - March 05, 2005 By Heather Hacking Experts say floods are likely, plan to live with them Chico Enterprise-Record ­ 3/5/05 By Heather Hacking, staff writer Reining in the rivers in the Sacramento Valley has been a decades-long battle, a fight that is costly and bound to fail, experts said at a conference about flooding held in Chico Friday. When settlers came to the valley in the early 1800s, the valley floor was a massive flood plain, explained Irv Schiffman, chair of River Partners, one of the sponsors of the program. The inland sea didn't drain until summer. Changes to the river meander deposited sediment that made rich soils. Over the past five decades, systematic efforts have been made to tame the river with levees, weirs and bypasses. Now every major river in the valley has dams. These efforts have kept things in check, for the most part, but big floods hitting Northern California are to be expected, Schiffman said. Stacy Cepello, of the Department of Water Resources in Red Bluff, said California is periodically hit with "major-league storms," usually coming from the tropics. Removing vegetation that acts as a sponge for floodwaters and paving over land means more water through the river systems, Cepello said. Disruption of the natural flows began in the 1850s during the gold-mining era and reached a peak with hydraulic mining. "The scale to which this happened is unbelievable," Cepello said. In the Feather River, for example, 2 million cubic yards of sediment went down the waterway in a year. During mining, up to 1.2 billion cubic yards washed downstream. Sacramento began to have a chronic flooding problem. The Army Corps of Engineers was overwhelmed and redesigned the system. The Sutter and Yolo bypasses were built to handle high flows and dams were built. Shasta Dam, for example, has reduced floods by about half, Cepello said. Tom Griggs, of River Partners, discussed the habitat that relies on land near waterways to survive. Root systems of trees along the banks can help stop erosion, he explained. The common yellow throat bird lives in cattails and woody vegetation and needs 2-3 feet of water. The black-headed grossbeak needs woody vegetation near wetlands. Bank swallows nest only in banks that are eroding. Song sparrows prefer herbaceous, weedy edges near water, habitat that is rapidly declining, Griggs said. Swainson's hawk requires tall trees for nesting and needs grasslands to hunt small mice and crickets. Yellow billed cuckoos are found only with open water and currently there are only 40-60 pairs in the Sacramento Valley, Griggs said. Jeffrey Mount, of the department of geology at UC Davis and a member of the Reclamation Board and Science Board with CalFed, said the nation has tried to eliminate flood plains, but has been unsuccessful. The system tries to move water quickly, but this has tremendous biological and economic consequences, Mount said. The national flood insurance system was created to map out what areas are likely to flood and to require flood insurance in those areas. The decision was made to designate areas as either in the 100-year flood plain or outside the 100-year flood plain. This decision has driven hundreds of billions of dollars of growth, "but it's all wrong," Mount said. "We have a distorted policy to put rivers inside levees," he said. But the 100-year flood maps are an assumption that the rivers won't flood for 100 years. There are only 60 years of flood records to go by, he said. The spiral of building more levees and dams just continues, he said. Scientists agree that climate changes are occurring. Because California gets half of its water supply from snowpack, a warming trend could wreak havoc on the state's water system. "Yet we're building whole cities and sewage treatment plants" and other infrastructure in areas where high water will eventually occur, Mount said. Natural flood plains are the best storage for floodwaters, Mount said. The deposit of river material improves soils for farming, he added. # http://www.chic oer.com/Stories/0,1413,135~25088~2746290,00.html