Flood in Pennington County, South Dakota

Runoff from heavy rain caused overland flooding and flooding along Rapid Creek, Box Elder Creek, Spring Creek, and tributaries of the Cheyenne River. A culvert washed out on Nike Road east of the Cobalt Drive intersection, water covered South Ellsworth Road south of Highway 14-16, 154th Avenue near 233rd Street, Creston Road south of SD Highway 44, Base Line Road south of Wasta, Bear Creek Road from SD Highway 44 to Sage Creek Road, and Paulson Road near Quinn. Several roads were inundated between Box Elder and New Underwood; including 155th avenue, 156th Avenue, 159th Avenue, and Sharpe Road. Street flooding was also reported in Rapid City and Rapid Valley along South Valley Drive, Green Valley Road, and Reservoir Road.

A powerful storm system slowly moved from the Four Corners region northeastward through the Plains, leading to a prolonged period of precipitation across western South Dakota May 20-22. This three day period was among the coldest, wettest, and snowiest on record for late May, with several temperature and precipitation records set. Runoff from the rain and melting snow led to flooding of creeks, rivers, low-lying areas, and some roads across western and south central South Dakota.