A rapid surge in St. Croix River levels will require boaters operating between Taylors Falls and Prescott, Wis., to slow down, according to the Minnesota Department of Natural Resources (DNR).

To reduce shoreline erosion, boaters must operate at no-wake speeds when the river’s level reaches 683 feet above sea level at Stillwater on Friday morning, the DNR said.

Officials from Minnesota, ­Wisconsin and the National Park Service will post signs on the slow no-wake requirement at all public accesses, and marina operators have been notified, the DNR said.

The slow no-wake rule will remain in effect until the water level recedes. Boaters can check the current river level online at mndnr.gov/nowake/.

The St. Croix is expected to peak Saturday or Sunday at 685.2 feet, slightly lower than minor flood stage and lower than forecast earlier this week.

Meanwhile, because of flood conditions, park rangers have closed river landings along the Namekagon and St. Croix rivers in the St. Croix National Scenic Riverway north of Stillwater.

Because of heavy rain in north central Minnesota and northern Wisconsin on July 11, many tributaries of the St. Croix, including the Namekagon, have overflowed their banks and are running dangerously high and fast, said acting superintendent Julie Galonska.

A high volume of water, along with debris, is now flowing downstream, she said.

Additional information on river conditions and closures is available at the Riverway website at nps.gov/sacn/.