SOUTH DAKOTA FLOW REPORT
Last Updated: January 1, 2026
South Dakota's rivers are currently experiencing a mix of low and extraordinarily high streamflows, presenting a range of conditions for water enthusiasts in the state. Notably, the Whetstone River near Big Stone City has recorded a dramatic streamflow of 29,300 cubic feet per second (cfs), a significant increase of 76,401.31 cfs over the last 24 hours, and is flowing at 2426.97% of its normal rate, indicating potential flooding concerns. Contrastingly, the Inlet Canal above Belle Fourche Reservoir and the Redwater River above Belle Fourche are experiencing a flow drought, with reductions of 11.11 cfs and -55.21% of their normal streamflow, respectively. These extreme variabilities in streamflow suggest that river conditions across the state are highly diverse, with some areas facing possible flood risks while others grapple with water scarcity.
The Cheyenne River watershed is showing mixed conditions, with the Cheyenne River near Wasta at 190 cfs (27.67% normal) and Redshirt with an elevated flow of 311 cfs, a recent surge of 304.95 cfs pushing it to 126.58% of its normal flow. The Belle Fourche River near Elm Springs also presents an abnormal flow rate at 17,900 cfs, reflecting a 727.05% increase from its normal rate, thus raising alarms for potential flooding in the surrounding areas. Meanwhile, the Big Sioux River, important for both Brookings and Sioux Falls, displays lower-than-normal flows with the Big Sioux R at North Cliff Ave at Sioux Falls recording 471 cfs, which is 45.16% of its expected flow. These diverse flow conditions could impact recreational activities like whitewater rafting, fishing, and the ecological health of the region. River-goers and local communities around these notable rivers should remain vigilant and informed about the current water levels and potential for rapidly changing conditions.
South Dakota has a humid continental climate with four distinct seasons. The Missouri River, which forms the eastern border of the state, is the largest and most significant surface flow. It is subject to extreme flooding during spring and summer due to snowmelt and heavy rainfall. Other major rivers include the Cheyenne, James, and Big Sioux. The state has several reservoirs and dams, including the Oahe, Fort Randall, and Big Bend dams, which provide flood control, irrigation, and hydroelectric power. South Dakota's hydrology is influenced by its topography, soil type, and vegetation cover, which affect the amount and rate of water infiltration and runoff. The state's snowpack and precipitation patterns are important factors in determining water availability and storage.