Flood — Dewey, South Dakota

2025-09-18 to 2025-09-19 · near Whitehorse, Dewey, South Dakota

Event narrative

The river gauge on the Little Moreau at Promise went above flood stage on the afternoon of September 18th, topping out at 23.03 feet (2.03 feet above flood stage) during the early morning hours of September 19th. The river fell below flood stage later that afternoon. Virgin Creek, which flows into the Little Moreau just before they enter the Missouri River, was flowing across Promise Road at a depth of over one foot.

Wider weather episode

Moderate to heavy rainfall occurred across a broad portion of Stanley and Dewey counties. The COOP observer 3 miles west southwest of Wendt would record a 2 day total of 4.94 while the CoCoRaHS observer in Fort Pierre received 4.06 over 3 days. This area had also received about an inch of rainfall on or around the 15th. Rainfall and saturated soils resulted in flooding of several streams and creeks, including the Bad River between Wendt and Fort Pierre, and Virgin Creek near Promise. Shelters were opened for homeowners impacted by rises in the Bad River in Fort Pierre, with portions of Bad River road seeing damage due to washouts. A stretch of BIA 8 east of Eagle Butte was also partly washed out.

View location on OpenStreetMap → (45.2500, -100.7500)

Source: NOAA Storm Events Database, event_id 1292970. Narrative written by the NWS forecast office that issued the report.