American River Watershed Investigation

This book reviews the U.S. Army Corps of Engineers' (USACE) investigations of flood control options for the American River basin and evaluates flood control feasibility studies for the watershed, with attention to the contingency assumptions, hydrologic methods, and other analyses supporting the flood control options. This book provides detailed comments on many technical issues, including a careful review of the 1991 National Research Council report American River Watershed Investigation, and looks beyond the Sacramento case to broader questions about the nation's approach to flood risk management. It discusses how to utilize information available about flood hazard reduction alternatives for the American River basin, the potential benefits provided by various alternatives, the impacts of alternatives on environmental resources and ecosystems, and the trade-offs inherent in any choice among alternatives which does not lie in the realm of scientists and engineers, but in the arena of public decisionmaking.

Sacramento, California, has grown literally at the edge of the Sacramento and American Rivers and for 150 years has struggled to protect itself from periodic floods by employing structural and land management measures. Much of the population lives behind levees, and most of the city's downtown business and government area is vulnerable to flooding. A major flood in 1986 served as impetus for efforts by federal, state, and local entities to identify an acceptable and feasible set of measures to increase Sacramento's level of safety from American River floods. Numerous options were identified in 1991 by the U.S. Army Corps of Engineers (USACE) in a report known as the American River Watershed Investigation. Due to the controversial nature of many of the alternatives identified in that report, study participants were not able to reach consensus on any of the flood control options. In response, the Congress directed the USACE to reevaluate available flood control options and, at the same time, asked the USACE to engage the National Research Council (NRC) as an independent advisor on these difficult studies. In 1995 NRC's Committee on Flood Control Alternatives in the American River Basin issued Flood Risk Management and the American River Basin: An Evaluation. This report outlined an approach for improving the selection of a flood risk reduction strategy from the many available.