SOUTH-DAKOTA RESERVOIR REPORT

Last Updated: January 1, 2026

In the latest observations across the nation's dams and reservoirs, a comprehensive assessment reveals a mixed landscape of water storage levels, with variances that reflect the diverse climatic conditions and water management strategies at play. Some regions are experiencing surpluses, while others face droughts, underscoring the importance of adaptive water management.

Among the reservoirs recording higher than average storage levels are Lake Almanor in California, which currently holds over a million acre-feet more than its average, signifying a surplus that benefits local ecosystems and water supply. Conversely, Lake Powell in Arizona reflects a stark deficit, with its storage levels falling approximately 8 million acre-feet short of the average, indicative of the prolonged drought affecting the Colorado River Basin. Similarly, New Mexico's Elephant Butte Reservoir storage is significantly below its historical average, echoing water scarcity concerns in the Southwest. These conditions not only impact water availability for human consumption but also have far-reaching effects on agriculture, hydroelectric power generation, and natural habitats. The variances in reservoir levels can often be traced back to factors such as snowpack levels, river flows, and regional precipitation patterns, which are influenced by broader climatic shifts and require ongoing monitoring and responsive water management strategies to ensure sustainable use and conservation of this vital resource.

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.