The river which is the second-largest source of algae-causing runoff in the St. Croix will see levels of harmful phosphorus decreased by 65 percent under a new plan.
The Willow River plan, created by St. Croix County, is expected to soon be approved by the U.S. Environmental Protection Agency and the Wisconsin Department of Natural Resources.
To achieve the plan’s goals, several groups will have to take steps to reduce pollution from farm fields, lawns and water treatment plants, the New Richmond News reports:
The largest contributing factor to the high phosphorus levels in the Willow River are agricultural fields that have been enhanced with fertilizer or manure, Kulow said. When rains come, those nutrients can wash into the river and cause problems for everyone downstream.
Another contributing factor is the villages and cities that discharge their sewage treatment effluent and storm water run-off into the Willow. New Richmond and Clear Lake are the two biggest municipal phosphorus dischargers along the length of the river. New Richmond currently meets EPA requirements but efforts to reduce phosphorus levels even more could be costly.
Homeowners along the river, and especially at Lake Mallalieu in Hudson, also add to the TMDL levels when lawn fertilizers with phosphorus end up in the water.
One other source of phosphorus is much more difficult to pinpoint. Decaying leaves and other material that drops into the river can add to the overall level.
The announcement comes on the heels of the St. Croix River’s own phosphorus-reduction plan being approved by the EPA in September. ‘
Because of the Willow’s significant contribution of phosphorus to the St. Croix, the smaller river’s plan is key to achieving the goal of a 360 metric tons/year of phosphorus in Lake St. Croix by 2020 — a 20 percent reduction from current levels.