Interstate 29 is closed from exit 4 to exit 26 between North Sioux City and Vermillion due to floodwater from the Big Sioux River.
The water will be diverted to McCook Lake underneath the exit 4 overpass. A levee is being constructed Thursday to divert the water.
The South Dakota governor’s office released maps of the detours for I-29.
Alternative route for traffic from north of Sioux Falls through Council Bluffs, IA:
• Southbound I-29 Interstate traffic will be detoured ontoI-90 east at Exit 84A at Sioux Falls, SD, then south on I-35 Exit 159A at Des Moines, IA, then west on I-80 at Exit 137A to Council Bluffs, IA, then to I-29 south.
• Northbound I-29 Interstate traffic will be detoured at Council Bluffs, IA onto I-80 eastbound, then north on I-35 in Iowa to Albert Lea, MN and west on I-90 to Sioux Falls.
Detour on local roads:
• Southbound I-29 traffic in South Dakota will be detoured onto SD 50 West at Exit 26 to Vermillion, then south to SD 19 into Nebraska where it becomes Highway 15, then continue south to Highway 12 east in Nebraska to U.S 20 east in Nebraska, then to Exit 1A for I-29 south at South Sioux City, NE.
• Northbound I-29 traffic will exit onto Highway 20 west, then north on Highway 12 and Highway 15 in Nebraska, continuing onto Highway 19 in South Dakota to the Vermillion Exit to SD 50 eastbound to I-29.
Travelers are urged to visit safetravelusa.com/SD or to call 511 to check latest road conditions in their area.
“As you’re traveling to South Dakota, you may have to take some detours; however, these highway closures will not prevent you from getting to your destination,” the South Dakota Department of Tourism said in a statement.
It is unclear when the interstate will reopen.