Slow no-wake speed means the slowest possible speed to maintain steerage, but no greater than 5 mph.
The rule requires that watercraft operate at slow, no-wake speeds, river wide, once the river reaches 683.0 feet MSL (Mean Sea Level) as measured at the gauge at Stillwater. Failure to comply may result in a citation from law enforcement patrols on the water. Once the river levels drop below 683.0 feet, the restrictions are lifted but boaters are cautioned that there continues to be hazards and shoreline erosion potential. The graph below starts at a datum of 600 MSL.
Slow-No-Wake zone around the St. Croix Crossing bridge project. (Mn/DOT)
In 1986 the St. Croix high water no-wake rules were implemented to apply to the 52 mile river stretch from the dam at Taylors Falls to Prescott. The measures were put in place to help protect boaters from flood related hazards such as floating debris and river currents. They also help minimize damage to shorelines, levees, and islands which are more vulnerable to damage from wakes during high water events.