Flash Flood — Brown, South Dakota

2007-05-05 to 2007-05-06 · near Warner, Brown, South Dakota

Event narrative

Very heavy rains of 5 to nearly 10 inches fell within a 6 to 10 hour period across most of Brown county causing widespread flash flooding. Most of the cities affected included Aberdeen, Warner, Columbia, Hecla, Groton, Barnard, Bath, and Stratford. Several hundred homes, some businesses, and countless roads were affected by the flooding. Aberdeen received the most extensive damage, especially the north side of Aberdeen. Seventy-five percent of the homes in Aberdeen received some water in their basements. Basement water levels ranged from a few inches to very deep water all the way up to the first floor of homes. Several homes had basement walls that collapsed. The overwhelming load on the drainage system caused sewage to back up into many homes. The National Guard brought large generators and pumps to Aberdeen to alleviate pressure on the storm system. A school in north Aberdeen was closed for several days because in was surrounded by water. Also, many vehicles stalled on the roads and power outages occurred, mainly in northern Aberdeen, as transformers went under water. Many cars were also damaged by the flooding. Over thirty families in Aberdeen were displaced from their homes with many living in emergency shelters.

Over one-hundred homes in Aberdeen were condemned with nearly fifty considered as unlivable. Thousands of acres of crops were flooded and damaged with many seeds and large quantities of fertilizer washed away.

An emergency operations center was operated in Aberdeen for several days to coordinate all emergency activities. Hundreds of volunteers helped with the cleanup. Over 2500 tons of flooding debris was taken to the landfill in Aberdeen. The Governor was in Aberdeen and declared a state of emergency for Brown county.

Groton, Stratford, Bath, Claremont, and Columbia also had flooded homes and basements. Thirty percent of Columbia's homes had some water in them with two collapsed basement walls. Eighty percent of Groton's homes had water in their basement with half having sewer backups. Sixty homes in Groton had major damage. Many sewer backups also occurred in Claremont.

Senator John Thune and representative Stephanie Herseth came to Brown County to survey the damage. Brown County was declared a disaster area by President Bush with disaster recovery and community assistance centers opened. Eight damage assessment teams from local, state, and FEMA came to Brown and other counties.

Rainfall amounts included 4.99 inches at Westport, 7.49 inches at Stratford, 7.97 inches at Aberdeen, 8.07 inches at Sand Lake Wildlife Refuge, 8.73 inches at Columbia, and 8.74 inches at Groton. Adding in the previous days rain, Aberdeen received 9.00 inches, Columbia received 10.19 inches, with 10.74 inches at Groton. The 8.74 inches of rainfall at Groton set a new 24 hour state rainfall record.

Wider weather episode

A large upper low pressure area in the southwest United States spun off a strong upper level disturbance into the northern plains. This disturbance lifting over the area along with a north to south frontal boundary, powerful low level winds, and abundant gulf moisture resulted in training thunderstorms across northeast South Dakota. The training thunderstorms produced anywhere from 3 to 10 inches of rainfall resulting in widespread flash flooding across Brown, Buffalo, Hand, Spink, Clark, Day, and Marshall counties. Brown, Buffalo, Clark, Day, Marshall, Spink were declared disaster areas by President Bush.

View location on OpenStreetMap → (45.3200, -98.5000)

Source: NOAA Storm Events Database, event_id 36405. Narrative written by the NWS forecast office that issued the report.