The water is rising in Union County and the interstate is closed to traffic. The closure is designed to protect homes but drivers heading south on Interstate 29 will have to change directions and follow a detour.
Workers built a temporary levee to connect the Big Sioux River to McCook Lake. The levee is under the overpass, so the water will go across the interstate and around Northshore Drive before it goes into McCook Lake.
Crews started diverting water around noon on Thursday.