Flood in Grant County, South Dakota

A broad low-pressure system brought several rounds of rain and a few strong, isolated thunderstorms to northeast South Dakota. The rain began on the morning of June 12th. A break in the rain mid-day allowed the atmosphere to destabilize, which led to stronger storms in the afternoon. One storm produced penny-sized hail 3 miles west of Blunt. Another storm in Mansfield produced penny to nickel-sized hail and winds strong enough to damage house siding and shingles.

Heavy rain continued across the region for the rest of the day and overnight. The highest public rainfall report was 7.46 inches. A CoCoRaHS observer in Claremont recorded 7.06 inches, while the COOP station in Wilmot measured 5.60 inches. Other reports included 5.25 inches near Lake City and 4.63 inches near Sisseton. The intense rain flooded parts of Roberts County, covering many county roads and several streets in the city of Sisseton. Several Sisseton businesses were damaged; at Gas Lakes, about 40 propane tanks were seen floating in the floodwater. The town of Wilmot also experienced significant flooding.

In addition to roads and businesses, several local rivers also flooded. The Little Minnesota River near Peever crested at 21.46 feet (4.46 feet above flood stage), primarily flooding farmland. Near Milbank, the North Fork Whetstone River crested at 1059.15 feet (3.15 feet above flood stage), with water nearly reaching the bottom of a local bridge. This river also mainly flooded agricultural land and remained above flood stage through June 16th.