Flooding in South Dakota, May 16 to 21, 2025

More seasonal rainfall was observed in middle to late May across north central South Dakota. A local area of moderate to heavy rain, between 4 to 6 inches, was observed with a system on May 15th and 16th, with the COOP observer located 8 miles south southwest of Keldron recording 5.6 inches of moisture. This would result in minor flooding of the Grand River, with the gauge near Little Eagle topping out at 15.43 feet, which is 0.43 feet above flood stage. Minor flooding of pastureland was the only impact observed with this rise in the river. The river would fall below flood stage within 24 hours, however another round of moisture would cause a second crest, this time at 0.48 feet above flood stage, on the 21st of May. The COOP observer 8 miles south southeast of Keldron would record an additional 2 inches of moisture leading up to this second crest. During this time, Oak Creek near Wakpala would also flood, reaching a peak of 11.51, or 1.51 feet above flood stage on May 21st. This would also only lead to minor flooding of nearby pasture.