IDAHO RESERVOIR REPORT

Last Updated: December 21, 2025

Idaho's dams and reservoirs are crucial for water storage, flood control, and recreational activities. Current observations indicate that some water bodies are experiencing abnormal conditions, with several reservoirs reporting gage heights below their respective averages for this time of year. Priest Lake, Henrys Lake, Milner Lake, Salmon River Canal Co Reservoir, Mud Lake, Mackay Reservoir, and Payette Lake are all showing lowered water levels, ranging from modest to significant decreases. For example, Priest Lake's gage height is nearly half of its average at 1 ft compared to the usual 1.95 ft. Similarly, the Salmon River Canal Co Reservoir is at a mere 9 ft, starkly lower than its average of 23.8 ft. These deviations could be linked to the recent climate trends, including a notably warmer fall, as reported by Spokane Public Radio, which may contribute to reduced snowpacks and subsequently impact river flows and reservoir levels.

Among the affected, Little Wood Reservoir's storage capacity is remarkably lower than average, with current levels at 13,380 acre-feet, falling short of the average 17,024 acre-feet. Conversely, Coeur d'Alene Lake is slightly above average, currently at 29 ft against the typical 25.98 ft. The unusual conditions across Idaho's dams and reservoirs may also relate to broader weather patterns impacting the region, including the weeklong lashing of rain and wind reported by The New York Times in California, and the state of emergency in Washington due to historic flooding driven by an atmospheric river, as detailed by AOL.com. These weather events can have downstream effects on regional water systems, influencing Idaho's reservoir conditions. The abnormal discrepancies in gage heights and storage levels at this point in the year warrant close monitoring, as they can affect water management decisions, ecological balance, and the availability of resources for communities and the environment.

Idaho has numerous reservoirs and dams that provide irrigation, hydropower, and recreational opportunities. Major reservoirs include Lucky Peak, Anderson Ranch, and American Falls. These reservoirs are fed by streams and rivers such as the Boise River, Snake River, and Portneuf River. The hydrology of the area is heavily influenced by snowfall in the surrounding mountains, particularly the Sawtooth and Rocky Mountains. Snowpack levels are closely monitored as they impact streamflow and reservoir levels. In recent years, drought conditions have led to lower snowpack levels and decreased reservoir levels. Record low levels have been seen in several reservoirs during drought years. Seasonal trends show higher reservoir levels during the spring and early summer due to snowmelt, with levels decreasing through the fall and winter. Overall, reservoirs and dams play a significant role in Idaho's water management and the state's economy.

Idaho has numerous reservoirs and dams that provide irrigation, hydropower, and recreational opportunities. Major reservoirs include Lucky Peak, Anderson Ranch, and American Falls. These reservoirs are fed by streams and rivers such as the Boise River, Snake River, and Portneuf River. The hydrology of the area is heavily influenced by snowfall in the surrounding mountains, particularly the Sawtooth and Rocky Mountains. Snowpack levels are closely monitored as they impact streamflow and reservoir levels. In recent years, drought conditions have led to lower snowpack levels and decreased reservoir levels. Record low levels have been seen in several reservoirs during drought years. Seasonal trends show higher reservoir levels during the spring and early summer due to snowmelt, with levels decreasing through the fall and winter. Overall, reservoirs and dams play a significant role in Idaho's water management and the state's economy.