Minor Flood Warning Issued for Mississippi River at Alton and Grafton

ALTON/GRAFTON/HARDIN - A stretch of the Mississippi River in the St. Louis region is forecast to climb into minor flood levels in the coming days, with the National Weather Service in St. Louis issuing a minor flood warning for the Mississippi River at the Mel Price Lock and Dam in Alton and the Mississippi River at St. Louis.

The forecasts, based on observed precipitation and forecast precipitation, show the Mississippi River at the Mel Price Lock and Dam in Alton is expected to rise above flood stage and crest at 23.5 feet Thursday evening, April 30, 2026, then begin to fall to 21.0 feet late Sunday evening, May 3, 2026. Minor flooding at the Mel Price Lock and Dam occurs when the river stands at 21.0 feet.

Farther north, the Mississippi River at Grafton is expected to crest at 23 feet on Monday, May 4, 2026. Minor flooding at Grafton stands at 21 feet. The river at Grafton is forecast to be at 22.41 feet on Wednesday, April 29, 2026.

On the Illinois River, the gauge at Hardin is expected to be at 28.3 feet at 7 p.m. Wednesday, April 29, 2026, and reach a high of 29.20 feet on Friday, May 1, 2026, before decreasing to 28.4 feet on May 5, 2026. Minor flooding for the Illinois River at Hardin is 25 feet.

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