Flood — Hamlin, South Dakota

2025-08-06 to 2025-08-10 · near Castlewood, Hamlin, South Dakota

Event narrative

The Big Sioux River near Castlewood entered flood stage around mid-day on August 6th. The river would crest at 1030 pm on August 7th at 10.63 feet, or 1.63 feet above flood stage. The river stayed in flood through the morning of August 10th. Flooding was mainly confined to low-lying agricultural lands north of Castlewood, though a portion of 184th street flooded.

Wider weather episode

Heavy rainfall of 2 to 4 inches across Codington and Hamlin counties, falling on already saturated soils due to above normal precipitation through the spring and summer months, resulted in flooding of the Big Sioux River and its tributaries including Mud and Willow Creeks. Flooding would mainly be limited to low spots and agricultural lands, however.

View location on OpenStreetMap → (44.8000, -97.0300)

Source: NOAA Storm Events Database, event_id 1290194. Narrative written by the NWS forecast office that issued the report.