Corps releases revised environmental report for Folsom Dam Raise project

Published June 16, 2017

SACRAMENTO, Calif. – The U.S. Army Corps of Engineers Sacramento District and Central Valley Flood Protection Board are recirculating for review a draft environmental impact statement/environmental impact report for the Folsom Dam Raise Project. 

The report was initially released in July 2016; however, it is being be recirculated for a second public review and comment period due to significant changes made since then.

While the proposed project evaluated in the original draft report has not changed, the revised report provides additional information and corrects erroneous information and data. The report addresses environmental impacts and recommends mitigation measures in regard to the proposed modifications at Folsom Lake, including: 

·         Tainter gate refinements – Refinements would include modifying eight Tainter gates located at the crest of the main dam (Folsom Dam). Other structural changes to the main dam would include: construction of new “top seal bulkheads” to prevent overtopping of the Tainter gates during a major flood event; construction of vertical concrete extensions to the dam’s 9 existing concrete piers to provide an elevated platform for a hoist system for the Tainter gates and mountings for the top seal bulkheads, and; installation of the hoist system.

·         Earthen raise elements – The existing crest elevation of Dikes 1 through 8 and the Mormon Island Auxiliary Dam would be raised by about 3.5 feet by adding earthen and rock materials to the top and upper sides of these features.

·         Concrete floodwall elements – A reinforced concrete floodwall would be built on top of the Left Wing Dam and Right Wing Dam, thereby raising the crest elevation of these embankment dams by roughly 3.5 feet.

The revised draft report is available on the project web site at  Public comments can be submitted until July 31, 2017.

Comments, questions, or requests for copies can be made through email to or by postal mail to: U.S. Army Corps of Engineers, Sacramento District, Attn: Ms. Victoria Hermanson, 1325 J Street, Sacramento, California 95814. All comments received concerning the draft SEIS/EIR will be considered and incorporated into the final SEIS/EIR, as appropriate.

The Dam Raise Project is part of the Corps’ Folsom Dam Modification Project, also called the Joint Federal Project, designed to implement dam safety and flood risk reduction features at Folsom Dam and associated facilities to help prevent catastrophic flooding in the Sacramento region.

Tyler Stalker

Release no. 17-014