MOOSE, Wyo. — The Bureau of Reclamation is increasing outflows from Jackson Lake, timed to coincide with the natural peak (high) flows, announced Grand Teton National Park this afternoon.
As higher temperatures across the basin are anticipated, Jackson Lake inflows, the Snake River, and major tributaries are forecasted to peak over the Memorial Day weekend.
The increased flow release from Jackson Lake is designed to maximize benefits to the Snake River ecosystem through Grand Teton National Park and downstream, while meeting water delivery requirements per the 1949 Snake River Compact. Peak flows are important for maintaining river health by moving and depositing sediment, wood, nutrients, and vegetation along river corridors.
According to the Bureau of Reclamation, outflow from Jackson Lake Dam will increase and stay steady at 3,500 cfs over the Memorial Day weekend, and then on Tuesday, May 31, will be reduced to 2,600 cfs. The last change in this series of adjustments is a reduction in outflow on Wednesday, June 1, to 2,100 cfs.
River users are advised to be aware of increasing flows on the Snake River and tributaries, and the possibility for new and changing river hazards as flows rise and recede through mid-June.
Jackson Lake storage is forecasted to reach a maximum of 45% full (6747 feet) in 2022. Park concessions with marina facilities, including Grand Teton Lodge Company and Signal Mountain Lodge, are likely to modify operations in accordance with forecasted low lake levels. The Colter Bay Marina and associated activities will not open in 2022. In addition, it is likely that impacts to Signal Mountain and Leek’s Marinas will occur as early as the end of August. Park visitors with motorized boats should note that recreation opportunities will be increasingly limited in the park. Jackson Lake boat ramp levels are available at here.
Due to drought conditions throughout the west, water supply in the form of reservoir storage is in critical need. The Jackson Lake Dam, located on the Snake River in Grand Teton, contractually provides irrigation and flood risk management for the Upper Snake Basin. The Jackson Lake Dam raises the water level of the natural lake by 39 feet.
According to the Bureau of Reclamation, the reservoir currently is 25% full and 40% of normal storage for the date. Outflow earlier this week was 2,100 cfs, and has been increased over several days to reach a peak outflow of 3,500 cfs.
For current river and reservoir data, visit Reclamation’s Hydromet website here.