PROJECT ALERT NOTICE (SD) Flooding in SE South Dakota

Date: Fri, 21 Sep 2018 10:57:41 EDT

Summary: Heavy rainfall in the last 24 hours along the border between SD and IA has resulted in flooding in the southeast corner of SD.

In the last 24 hours, 3-6 inches of rain near the border between South Dakota and Iowa has produced minor to major flooding in the southeast corner of South Dakota. Precipitation information is available at:

https://data.cocorahs.org/cocorahs/maps/?country=USA&state=SD&lat=43.3322&lon=-96.8035&date=9/20/2018

Major flood stage has been reached or is forecasted for three stations on the Big Sioux and Vermillion Rivers. Moderate flood stage has been reached or is forecasted for five additional stations on the James, Vermillion, and Split Rock Creek. Minor flooding is occurring at four other stations.

The annual exceedance probabilities (AEP) for the flood crests at the USGS streamgages on the lower Big Sioux, James, and Vermillion Rivers are forecasted to be in the 0.10 ("10-year recurrence interval").

All streamgages are operational.

Field staff from Huron (2 crews) are completing discharge measurements using conventional and acoustic equipment. Staff will work this weekend as needed.

Stakeholders are being informed of our activities through updates to NWISWeb. Information is being shared with partners through NWSChat.