Corps releases final environmental report for Folsom Dam Raise project

Published Oct. 11, 2017

SACRAMENTO, Calif. – The U.S. Army Corps of Engineers Sacramento District has published the final environmental impact statement/environmental impact report for the Folsom Dam Raise project.

The report addresses environmental impacts and recommends mitigation measures in regard to the proposed modifications at Folsom Lake. Components of the dam raise project, designed to help reduce flood risk to the Sacramento region, include:

  • Tainter Gate Refinements – Modification of 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 nine existing concrete piers to provide an elevated platform for a hoist system for the Tainter gates and to provide 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 Final SEIS/EIR can be reviewed at 

Requests for copies of this document 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.

Tyler Stalker

Release no. 17-036