Broken Levees Make Forecasts Difficult As South Dakota Flood Waters Flow Toward River Country

DELL RAPIDS - The South Dakota Department of Transportation posted Thursday that a section of Interstate 90 between Plankington and Sioux Falls has been closed due to flooding.

Officials say floodwaters continue to rise and crews continue to monitor roadways and bridges.

An auxiliary spillway at a lake in Alexandria, S.D., was compromised just before noon on Thursday. The lake is draining into the James River.

A spillway at Lake Platte, also in South Dakota, was reported compromised earlier in the day.

The Missouri River Basin forecasting center in Pleasant Hill indicates major flooding on 10 locations upstream of Sioux Falls and moderate flooding at six other locations.  The Big Sioux River near Dell Rapids is project to exceed the record height by a couple of inches. The river is project to rise more 8 feet to a new record high of 16.7 feet.

The US Army Corps of Engineers say flooding remains at an elevated risk until the levee system is fully repaired.

The Missouri River went above flood stage at Nebraska City on March 13 and has remained. The river is expected to rise to 20.6 feet by Wednesday.