BILLINGS, Mont. - The Bureau of Reclamation updated the water supply forecast for the remainder of summer and projects lower reservoir levels and reduced river releases at most Reclamation facilities. The projected reservoir levels and releases have potential impacts to irrigation, recreation, and fishing activities at Reclamation facilities throughout Montana due to ongoing drought conditions impacting the Western United States.
While snowpack numbers were near average early in the year, dry antecedent conditions, below-average rainfall and above average temperatures over the last three months have driven current drought conditions. These drier conditions are reflected in the U.S. Drought Monitor report released by the National Drought Mitigation Center June 8, 2021. Most of the state is classified as ranging between abnormally dry to extreme drought.
The June through July water supply forecasts in Southwestern Montana range from 43 percent of average at Clark Canyon Reservoir and Bighorn Reservoir, to 49 percent of average at Canyon Ferry Reservoir. Forecasts are higher in the Sun, Marias, and St. Mary River Basins ranging from 73 to 95 percent of average. Reclamation’s Milk River project along Montana’s highline is expected to see below average conditions with inflows into Fresno Reservoir forecasted at 66 percent of average.
Both river and reservoir interests should expect to see lower than desired reservoir levels and releases this summer. One of the state’s more popular recreation destinations, Canyon Ferry Reservoir, is expected to peak 5-7 feet below the normal full pool elevation mark by the month’s end and releases to the Missouri River below Holter Dam are expected to be near the minimum, 3,000 - 3,400 cfs, for the remainder of the summer. Bighorn Reservoir and River within the Bighorn Canyon National Recreation Area will have similar conditions, with the reservoir projected to be approximately 10-feet short of filling this summer. Releases from the Bighorn River are projected at 1,750 cfs or less for an extended period.
Recreation is not the only interest being affected by the developing drought conditions, as several irrigation districts and their irrigators are living with reduced irrigation allotments. The East Bench Irrigation Project and the Milk River Irrigation Project are among the greatest impacted. The water shortages are impacting all water users and Reclamation is balancing all interests during these dry conditions.
Reclamation continues to collaborate with its many customers, stakeholders, and other partners across the agency to develop appropriate mitigation strategies for increased risks of drought and changes to precipitation, runoff, and increased water temperatures. These strategies include supporting reliable water deliveries through construction activities, water management improvements, improving hydropower generation capability, flexibility, and reliability through new, advanced decision support tools, and maintaining healthy ecosystems while protecting federally-listed fish, wildlife, and plants.
“Drought is a common occurrence in the Western United States and takes its toll on all resources while affecting people, the environment and infrastructure," said Ryan Newman, Montana Area Manager. “Reclamation’s scientists and engineers are working daily to reduce negative drought impacts and continue to champion best practices for water operations management."
For current Missouri River Basin water supply reports visit https://www.usbr.gov/gp/lakes_reservoirs/wareprts/wsrp.html.
Source: Bureau of Reclamation
