BUTTE - According to officials, water levels at Hebgen Reservoir will be low this summer and fall.
April snow and rain only minimally improved conditions in the Madison River Basin, which is experiencing extreme drought, low soil moisture and low snowpack. Based on the U.S. Natural Resources Conservation Service May-July runoff forecast and NorthWestern Energy’s forecasting tools, this will be another challenging summer and fall due to lack of water.
Hebgen Reservoir is currently at an elevation of 6,526.07 feet, which is 8.80 feet from the full pool. Inflows into Hebgen throughout the winter have been 82 percent of normal, while snowpack in the Madison basin above Hebgen Reservoir is at 82 percent of normal levels [wcc.sc.egov.usda.gov] and precipitation for the water year that began Oct. 1, 2021, is at 88 percent of normal levels. [wcc.sc.egov.usda.gov]
NorthWestern Energy was allowed to reduce Hebgen Dam water releases during April to the Madison River resulting in the capture of more water in Hebgen Reservoir, raising the level by 0.99 feet. This was a modification of the terms of our Federal Energy Regulatory Commission operating license and was only allowed for a short time.
“Saving this water to supplement flows on the Madison River during the heat of the summer will help to reduce stress on fish from elevated water temperatures,” said NorthWestern Energy Manager of Hydro License Compliance Andy Welch. “We are also working with our stakeholders to acquire a variance from our FERC license that will allow NorthWestern to increase releases more quickly from both Hebgen and Madison dams. This variance will result in significant water savings while we provide thermal pulses to the lower Madison River, which is critical for minimizing water temperatures for fish in the summer.”
Instead of increasing outflows from Madison Dam for pulse flows over four or more hours, NorthWestern Energy would be able to increase releases over a short duration leading to significant conservation of water. The variance, if approved by FERC, will also promote a faster response in flow releases from Hebgen Dam to accommodate changing conditions downstream such as shifts in weather or irrigation withdrawals. Slower flow reductions from both Hebgen and Madison dams, as required by our FERC license, will remain in effect in order to protect fish from stranding.
“NorthWestern Energy continues to monitor conditions and forecasts closely, but this will be another extremely challenging year without enough water to meet the needs of all the Madison River Basin users. I fully expect that we will not be able to maintain Hebgen Reservoir recreation elevations again this summer,” NorthWestern Energy Director of Hydro Operations Jeremy Clotfelter said. “We are exploring all options now for short-term management. Long term, stakeholders are being engaged to collaborate on low water management plans.”
More than 70 community members, business owners and other stakeholders met on April 26 in Ennis to hear presentations on the snowpack/runoff forecasts, fish population status, Madison fisheries TAC projects and more.
“We appreciate the time all those who attended invested to engage with NorthWestern Energy staff and other stakeholders,” said Clotfelter. “It’s an opportunity for our staff to hear concerns and receive feedback, which is critical as we all work together during another challenging low water year and work on long-term management plans.”
Current water levels at Hebgen Lake and flows and water temperatures are available at http://madisondss.com/page/dashboard.php
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