Heavy rains late last week led to inevitable flooding throughout South Dakota, prompting Gov. Kristi Noem to sign an emergency declaration Saturday.

“Even though the rain is slowing down, we need to keep vigilant. The worst of the flooding along our rivers will be Monday and Tuesday,” Noem said in a prepared statement posted to the governor’s website over the weekend. “Check SD511.org for updates on road conditions, and please reach out to your county emergency manager if you have immediate needs.”

The governor’s declaration also includes a “no boating” order impacting Lake Alvin, Lake Henry, Marindahl Lake, Menno Lake, Swan Lake, Wall Lake and Lake Vermillion.

The city of Sioux Falls issued an emergency declaration of its own Saturday, and Mayor Paul TenHaken said six people required help from emergency responders, including one who had to be rescued from near the falls along the Big Sioux River. The city of Sioux Falls also reported their wastewater facilities were operating at four times the usual rate of flow, and residents there were asked to avoid doing their dishes, washing laundry, or taking showers until the system can recover fully. 

The official Sioux Falls city website reports that, “minor amounts of untreated wastewater, heavily diluted by rain, began being discharged into the Big Sioux River” on Saturday. 

The governor encouraged people impacted by the flooding to carefully document any property damages and relay that information to insurance agents as well as local county emergency management offices. The state plans to collect and use that information when applying for assistance from the Federal Emergency Management Agency. 

According to Noem, rainfall totals from the recent deluge exceeded 18 inches in Canton. Elsewhere in South Dakota, more than 7 inches were reported in Mitchell, Sioux Falls, and Chamberlain. The four-day rainfall total for the Brookings area was estimated at more than 7 inches.

Bob Perry, South Dakota secretary of public safety, said a portion of Interstate 29 south of the Canton exit had to be closed over the weekend due to the flooding. 

He urged motorists to check the SD511 website or mobile app in order to stay up-to-date on road closures and no-travel advisories. 

The state department of transportation has also asked motorists to avoid driving around barricades or seeking to go down flooded, secondary highways in order to avoid road closures.