Although it's still early in the spring, NorthWestern Energy is already preparing for low water in the Madison River Basin.
The company announced on Monday it would reduce Hebgen Dam water releases from April 4-24 to the Madison in order to capture more water in Hebgen Reservoir.
Persistent drought conditions, low soil moisture and low snowpack were cited as reasons. With drought conditions extending across most of the state, Hebgen Reservoir is currently at an elevation of 6,524.6 feet, which is 10.3 feet from full pool, Northwestern reported.
Inflows into Hebgen throughout the winter have been 79% of normal, while snowpack in the Madison River Basin is at 76% of normal. Precipitation for the water year that began Oct. 1, 2021, is at 89% of normal.
In January, Hebgen Lake business owners filed a protest with the Federal Energy Regulatory Commission criticizing NorthWestern Energy’s management saying low water levels during the summer were irresponsible and hurt their operations.
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That news came on the heels of a December gate failure at Hebgen Dam that precipitously cut flows into the Madison River, stranding some fish and exposing some trout eggs to air. River flows fell from 648 cubic feet per second to 278 cfs in 15 minutes, a 57% reduction. It was about 46 hours before the gate was repaired and flows were restored.
Under Northwestern's plan, upper Madison River flows may be reduced to 550 cubic feet per second at the Kirby U.S. Geological Survey gauge and to 950 cfs below Madison Dam at the McAllister USGS gauge.
Under its federal license, Northwestern is supposed to maintain flows at Kirby Ranch at no less than 600 cfs.
The public is asked to avoid walking on any rainbow trout spawning beds during the low flows.
A public meeting will be held from 6-8 p.m. on April 26 at the El Western in Ennis to discuss the Madison River, snowpack, streamflow forecasts, fish populations, the Hebgen Dam gate malfunction and the projects sponsored by the Madison Fisheries Technical Advisory Committee.
“NorthWestern Energy and our stakeholders decided to move forward with this plan to conserve water now to allow for that water to be used later in the year,” Andy Welch, NorthWestern Energy manager of Hydro License Compliance, said in a press release. “Saving this water to supplement flows during the heat of the summer will help to reduce stress on fish from elevated water temperatures.”
“These management challenges are exacerbated when we are coming off a drought year like last year and into what is shaping up to be another challenging year,” Mike Bias, Fishing Outfitters Association of Montana executive director, said in the Northwestern press release. “Reducing flows out of Hebgen now to hopefully maintain adequate flows on the Madison through the summer and into fall is a necessary management decision, although, not an easy one. We know too that NorthWestern Energy does not make this management decision in a vacuum. Montana's Fish, Wildlife & Parks, BLM, and the Forest Service fisheries managers all think this is the best course of action at this time.”
Hebgen Reservoir water is used to control the flows on the upper and lower Madison River year round to protect and maintain the long-term health of the river system and the fishery.
Current water levels at Hebgen Lake and flows and water temperatures are available at http://madisondss.com/page/dashboard.php.
