Overhaul planned for Hungry Horse Dam power plant

The Hungry Horse Dam, which celebrated its 65th birthday this summer, needs a power-plant overhaul that will cost somewhere between $150 million and $200 million.

The U.S. Bureau of Reclamation has identified a preferred approach that will focus work on two of the facility’s four generating units simultaneously for one year and individual generating units for nine years.

The bureau said many of the power-plant’s components “have reached or exceeded their intended service life.” It said age-related wear “could potentially result in increased failures and longer forced outages, more challenging repairs due to obsolescence and unavailability of spare parts, and higher operation and maintenance costs.”

The 564-foot high Hungry Horse Dam is on the South Fork of the Flathead River, about 5 miles upstream from its confluence with the Flathead River. It provides water storage used for hydroelectric power production. Its reservoir provides flood control and its four generators produce electricity for Kalispell, Whitefish and Columbia Falls.

At full pool, the reservoir is 35 miles long and covers a surface area of 23,800 acres, the bureau said.

The overhaul work also will replace five of six cranes at the dam. The bureau said the cranes “need to be replaced or upgraded.”

An environmental assessment of the preferred alternative for overhauling the generators found that its implementation “will have no significant effect on the quality of the human environment or natural resources.”

And it should not unduly impact power generation, the bureau said. “Having three generating units available, which would occur in all but one year of the project under this alternative, is how Hungry Horse currently operates, given the electricity transmission limitations in the valley.” The bureau attributed transmission restrictions to the shutdown of the Columbia Falls aluminum plant.

There might be periods during the overhaul when spill from the dam increases “total dissolved gas” in the waters downstream. The bureau identified some strategies to mitigate this potential to protect fisheries.

Most funding will come from the Bonneville Power Administration, with some money from Congressional appropriations. Contractors will be selected through open bidding. Projects will be solicited on FedBizOps.

Onsite work is expected to begin in 2020.

Reporter Duncan Adams may be reached at dadams@dailyinterlake.com or 758-4407.