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Water release from Hebgen Dam to flush Madison River sediments

May 26, 2020

Butte, Mont. – May 26, 2020– NorthWestern Energy will release water from Hebgen Dam to flush fine sediments from Madison River gravel to maintain the quality of spawning gravels that support the healthy wild trout fishery.

The Madison River Flushing Flow Program was designed during U.S. Federal Energy Regulatory Commission licensing to augment natural flows with surplus water in good snowpack years. The 2020 flushing release from Hebgen Dam is a cooperative effort planned by NorthWestern Energy, Montana Fish, Wildlife & Parks, and the U.S. Forest Service.

Hebgen Dam outflows will be gradually increased to maximize releases for a minimum of three days coinciding with peak runoff in the West Fork Madison River and other tributary streams. To protect the outlet of Quake Lake from erosion, the Madison River flows will be maintained at about 3,500 cubic feet per second at the Kirby Ranch stream gage.

The flow releases should increase in early June with the exact timing based upon weather and snowmelt runoff.  River recreationists should be aware of the changing conditions and take appropriate precautions.  After the flushing event, the flow will be gradually tapered down to protect small fish and river life at the margins of the stream.

Questions about this flushing flow operation may be directed to NorthWestern Energy Manager Hydro License Compliance Andy Welch at 406-444-8115.

NorthWestern Energy owns and operates Hebgen and Madison dams on the Madison River under a license issued by the Federal Energy Regulatory Commission. The operation of the hydroelectric facilities play a significant role in managing streamflow on the Madison River.

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About NorthWestern Energy (NYSE: NWE)
NorthWestern provides electricity and / or natural gas to approximately 734,800 customers in Montana, South Dakota, and Nebraska. We have generated and distributed electricity in South Dakota and distributed natural gas in South Dakota and Nebraska since 1923 and have generated and distributed electricity and distributed natural gas in Montana since 2002. More information on NorthWestern is available on the company’s website at

Media Contact:
Jo Dee Black
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