THE US ARMY CORPS OF Engineers (USACE) has thrown its support behind the proposal to raise the height of Folsom dam by 2.1m as a means of increasing flood protection for the City of Sacramento in California, US.

The agency’s conclusion was published in a recently released report American River Watershed, California, Long-Term Study. The report describes, analyses, and reports on the impacts of flood damage reduction and ecosystem restoration along the American river in Sacramento.

The proposal involves operating the dam at a raised flood pool elevation by increasing the available storage for detention. Among the required structural modifications to the dam are increasing the height of the concrete dam by the construction of a parapet wall, raising the wing dams and dikes, replacement of the existing spillway gates with larger gates, as well as modifications to the bridge across the spillway. The existing gravity concrete dam stands 105m above the foundation, and the powerhouse with a capacity of 198MW develops about 10% of the power used in Sacramento each year Meanwhile in Washington, US, Congressman Robert Matsui, a supporter of the proposal, told the US House of Representatives that raising the Folsom Dam is the right plan for protecting Sacramento. However, Republican Congressman John Doolittle opposes the estimated US$219M project, claiming that the proposal does not provide enough protection.

Doolittle favours construction of a multipurpose dam at Auburn and is fighting the Folsom project because he thinks it would detract from the cost justification of the larger upstream dam that also would provide water storage, generate power and expand recreational opportunities.