BLM breaks ground on Grub Dam rehabilitation GAOA project

Story by Gina Baltrusch, Public Affairs Specialist, North Central MT District

Great American Outdoors Act funding is giving the Bureau of Land Management’s Grub Dam a new lease on life in Valley County, Montana.

brown dry land surrounds water at a dam
Rehabilitation work on the Bureau of
Land Management’s Grub Dam in
Valley County, Montana, will include
replacing the existing steel outlet works
with a reinforced concrete outlet works
to mitigate potential dam failure.
BLM 2014 file photo.

Workers recently broke ground on a rehabilitation project to restore the 58-year-old dam, which attracts many recreational visitors to its approximately 690-surface-acre reservoir amidst more than 500,000 acres of BLM-managed lands. Located about 22 miles southwest of Glasgow, the dam also serves as a portion of Beaver Branch Road and provides critical transportation infrastructure for the public.

Grub dam is also crucial for providing a consistent water source for wildlife habitat, wildfire suppression and livestock grazing. At full pool, the reservoir can store up to 4,054.3 acre-feet of water – enough to fill more than 2000 Olympic-sized swimming pools.

Heavy equipment is being used to dig up the ground.
Contractors dig into the Grub Dam
rehabilitation project June 28, 2022,
removing the old gabions and earthen
material to access and remove the old
outlet works. The steel-mesh-enclosed,
rock-filled gabions armor the dam face
from degradation caused by wave action
in the reservoir. Photo by Dean Jensen,
BLM Glasgow Field Office civil engineer.

Original construction of the 2,339-feet-long, 21-feet-high, earthen-filled gravity dam was completed in 1964 for the primary purpose of flood-risk reduction in the Milk River Basin. Grub reservoir also has a riparian area that provides habitat for many wildlife species. If left unrepaired, the dam posed a safety risk to the recreating public, as well as possible liability from potential flood damage to downstream access roads and grazing allotments.

The reconstruction project is helping BLM plan for the future by modernizing the dam’s infrastructure. Modernization features of the Grub Dam project include replacing the existing steel outlet works with a reinforced concrete outlet works to mitigate potential dam failure, according to Mike Borgreen, BLM’s acting Glasgow Field Office manager. And, the work involved with accomplishing that challenged normal operating budgets.

“We had to defer maintenance on the dam for several years, and thanks to GAOA funding, we now can make Grub Dam safer and better than ever,” said Borgreen.

The Great American Outdoors Act (GAOA, Public Law 116-152) was signed into law on August 4, 2020, providing major investments to address deferred maintenance needs, increase recreational access to our public lands, and conserve our lands and waters. The Grub Dam rehabilitation project is one of 13 projects in Montana designated to receive GAOA funding – https://www.blm.gov/about/laws-and-regulations/infrastructure/great-american-outdoors-act

A $1.53-million contract to perform the work was awarded March 8, 2022, to Youderian Construction Inc., a registered small business based in Stanford, Montana.

Some of the major work items include dewatering the reservoir and construction area, excavating a portion of the existing dam embankment and foundation to remove the old outlet works, constructing the new outlet works, replacing and compacting the foundation and embankment materials, constructing a new principal spillway and restoring the road surface across the dam. Contractors will also reclaim all disturbed areas, including staging areas and temporary roads, preparing the work site for reseeding.

Work is on track for completion by the end of October.