NorthWestern Energy hired Morrison-Maierle to help with the Holter Dam’s spillway concrete repair. Holter Dam is a 1,364-foot-long and 124-foot-high concrete embankment dam on the Missouri River near Wolf Creek, Montana. NorthWestern Energy owns and operates the facility as a part of its Montana Integrated Hydro system.

Completed in 1918, the Holter Dam has provided electricity for more than a century, and it supplies electricity to more than 300,000 residential and commercial customers in Montana.

After 100 years of severe weather exposure, extreme temperatures, freeze-thaw exposure, and wind, waves, and spray from Holter Lake, the concrete spillway bays were in dire need of rehabilitation.