Hoeven Working to Advance $1.8 Billion Safety Modification Project for Garrison Dam Spillway

Hoeven Working to Advance $1.8 Billion Safety Modification Project for Garrison Dam Spillway

Senator Secured Funding for Project Design to Address Safety Concerns Highlighted by 2011 Flood; Construction to Start in 2029

GARRISON, N.D. - Senator John Hoeven and officials from the U.S. Army Corps of Engineers today reviewed the $1.8 billion spillway safety project that's being undertaken at Garrison Dam. The modifications:

• Will ensure the integrity of the Garrison Dam, which is the largest mainstream dam on the Missouri River, with Lake Sakakawea currently being the largest reservoir operated by the Army Corps by volume.
• Are needed to protect against multiple long-term issues that could result in uncontrolled releases from the dam, posing a significant risk to the downstream area.
  • These potential safety concerns were brought to light due to record flows that occurred during the 2011 flood.
  • A subsequent study recommended the full replacement of the spillway's drainage system, a reinforced concrete overlay in the spillway chute and various other safety-related modifications
• Are currently undergoing Preconstruction Engineering and Design (PED), which began in 2023 utilizing funding Hoeven secured as a member of the Senate Energy and Water Development Appropriations Committee.
  • The PED phase will involve six years of field investigations to inform the design, with construction expected to start in 2029.
  • Hoeven has provided nearly $13 million for the project's design phase to date, and included $32 million in additional PED funding in the Senate's Fiscal Year (FY) 2025 appropriations legislation.

"The Garrison Dam, along with the Lake Sakakawea and Lake Audubon reservoirs, are critical infrastructure for our state, helping ensure a reliable water supply for communities and agriculture, while supporting recreation and tourism. At the same time, a key function of the dam is to control Missouri River water levels, providing certainty to the region and protecting against the risk of flooding," said Hoeven. "The historic water flows during the 2011 flood revealed that the spillway needs modifications to ensure the dam's long-term integrity. That's why we've been working to fund the pre-construction and design phase of this project to address these potential safety concerns as soon as possible."

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