SOUTH-DAKOTA RESERVOIR REPORT

Last Updated: January 11, 2026

Across the nation, dams and reservoirs play a critical role in water management, serving as essential sources for irrigation, drinking water, and hydroelectric power, as well as providing flood control and recreational opportunities. A comprehensive analysis of the latest data reveals significant variations in storage levels, indicating the diverse hydrological challenges different regions are facing.

For instance, in New Hampshire, Lake Winnipesaukee at Weirs Beach is experiencing lower gage heights than its average, reflecting potential concerns for local water supply and recreation. Similar trends are seen in Colorado's Dillon Reservoir and Granby Reservoir, where storage levels are below average, potentially impacting water allocations downstream. Conversely, California's Berryessa and New Bullards Bar reservoirs are exhibiting higher than average storage, which could be attributed to effective water conservation measures or recent precipitation patterns.

Drought conditions are notably affecting several major reservoirs. Elephant Butte Reservoir in New Mexico and Lake Powell in Arizona are holding significantly less water than their historical averages, reflecting the prolonged impact of dry conditions in the Southwest. Similarly, Utah's Lake Powell and Flaming Gorge Reservoir report lower storage, which may have implications for future water availability in the region.

In contrast, some reservoirs are reporting above-average storage levels, such as New Mexico's Santa Rosa Reservoir and Colorado's Vallecito Reservoir, suggesting surplus from recent rainfall or snowmelt. This surplus could offer temporary relief for local water demands and support ecological habitats.

This snapshot of the nation's dams and reservoirs underscores the importance of continued monitoring and adaptive water management strategies to address both surpluses and shortages. Water management researchers and hydrologists will need to consider these fluctuating conditions as they plan for sustainable water use and prepare for the challenges posed by climate variability and change.

South Dakota has over 150 reservoirs and dams, with major reservoirs including Oahe, Sharpe, Francis Case, and Lewis and Clark. These reservoirs are fed by tributaries of the Missouri River, such as the James, White, and Cheyenne rivers. Snowpack in the Rocky Mountains, especially in Colorado and Wyoming, is a major source of water for these tributaries. Hydrology in the area is heavily influenced by seasonal trends, with high flows in the spring due to snowmelt and lower flows in the summer and fall. There have been several record high flows in recent years, including the historic flooding of the Missouri River in 2011. Drought conditions have also been an issue in some areas, leading to decreased water levels and increased concern for water use.

South Dakota has over 150 reservoirs and dams, with major reservoirs including Oahe, Sharpe, Francis Case, and Lewis and Clark. These reservoirs are fed by tributaries of the Missouri River, such as the James, White, and Cheyenne rivers. Snowpack in the Rocky Mountains, especially in Colorado and Wyoming, is a major source of water for these tributaries. Hydrology in the area is heavily influenced by seasonal trends, with high flows in the spring due to snowmelt and lower flows in the summer and fall. There have been several record high flows in recent years, including the historic flooding of the Missouri River in 2011. Drought conditions have also been an issue in some areas, leading to decreased water levels and increased concern for water use.