Bighorn Lake Water Supply Forecast

BILLINGS, Mont. - The Bureau of Reclamation reports that April-July inflows into Bighorn Lake are forecasted to be well below average in 2026. Based on March 1 conditions, inflows are projected at 612,000 acre-feet under median conditions-about 49 percent of the 30-year average. The forecast includes releases from Boysen and Buffalo Bill Reservoirs as well as natural gains and water use between the upstream reservoirs and Bighorn Lake. Unless conditions improve significantly, Bighorn Lake is not expected to fill this year, and the reduced water supply will impact both lake levels and releases to the Bighorn River.

"Water supply conditions across the Bighorn Basin are a growing concern this year," said Ryan Newman, Reclamation Montana Area Office Manager. "We are closely monitoring inflows and snowpack, and we'll continue coordinating with our partners and water users as conditions evolve. Public safety and responsible water management remain our top priorities."

Mountain snowpack in the basin above Bighorn Lake is currently at 80 percent of median according to the Natural Resources Conservation Service. However, the lower elevations of the basin have accumulated little to no meaningful snowpack. Drought conditions have intensified as the region has experienced drier and warmer-than-normal weather since the start of the year.

Releases to the Bighorn River were reduced to 1,750 cfs on Tuesday, March 24. April through June are typically the wettest months of the year. Precipitation during this period will play a critical role in either improving or worsening current conditions.

Current Conditions at Reclamation Facilities

Boysen Reservoir - Water storage remains below average for this time of year. Under the median inflow forecast, Boysen Reservoir is not expected to fill, and releases beyond irrigation demand are not anticipated.

Buffalo Bill Reservoir - Water storage is below average for this time of year. Under the median inflow forecast, Buffalo Bill is expected to fill.

Bighorn Lake - Water storage is currently above average for this time of year. Under the median forecast, Bighorn Lake is not expected to fill.

For more information, visit Reclamation's Montana Area Office website at, https://www.usbr.gov/gp/mtao/.