Mormon Island Auxiliary Dam closed to public until Spring 2025

Published May 1, 2024
Updated: May 1, 2024
A view of a lake with an earthen dike in the foreground, protected by a chain link fence, and the blue sky with clouds

A view of Folsom Dam Dike 1, located in Granite Bay, California, with Folsom Lake in the distance, November 15, 2023. The U.S. Army Corps of Engineers Sacramento District is raising the dike up to 3.5 feet in accordance with the overall plan for the Folsom Dam Raise project, which calls for similar raises across the dam system. Dike 8 was raised in 2020, and the district plans to complete the remaining seven dikes by 2027.

The U.S. Army Corps of Engineers Sacramento District has begun modifications on Mormon Island Auxiliary Dam (MIAD) in association with the Folsom Dam Raise Project, and public access to the area is now closed until mid-2025.

USACE began work April 9 to raise the dam approximately 3.5 feet through a combination of an earthen raise to the structure and installing concrete floodwalls. Areas that are temporarily inaccessible include the crest, parking lot, and trails within the construction zone along Green Valley Road.  Currently, there are no detours or trail connections available within Folsom Lake State Recreation Area. These areas are currently estimated to reopen in Spring 2025.

Similarly, all eight dikes that surround Folsom Lake are to be raised by as much as 3.5 feet as part of the project. Dike 8 was completed in 2020. The left- and right-wing dams and the main dam will also call for similar modifications.

The purpose of the Folsom Dam Raise is to reduce flood risk in the Greater Sacramento area by enhancing the utilization of Folsom Lake’s surcharge flood storage space and increasing the temporary water storage space used during major flood events.

The project is expected to be completed in 2028.

For more up-to-date information on USACE construction impacts near Folsom State Recreation Area, please save the following links:

  • USACE Sacramento District website:
  • USACE Sacramento District Facebook:
  • USACE Sacramento District X:
  • California Department of Parks and Recreation, Folsom State Recreation Area:

Samantha Boyle

Release no. 24-007