Algae bloom at Kinnickinnic River Beach, photo taken August 11, 2013 (courtesy MN DNR)
Boaters on Lake St. Croix have seen the river turn the color of antifreeze this month. Bright green algae has been spotted in the last several miles of the river above its confluence with the Mississippi.
Such algae can be harmful to people and animals. While most people wouldn’t get in water looking like that, it’s important to make sure pets stay away.
The algae is the result of too many nutrients in runoff from fields, streets, lawns, and wastewater treatment plants. Water like this is why the St. Croix has been designated as an impaired river. Deb Ryun, executive director of the St. Croix River Association, said the algae is an issue which must be addressed.
“Green water in August is not ‘normal,’ as some have come to think,” Ryun said. “We can and should do better, which is why it’s so important we work collaboratively to improve the water in Lake St. Croix. The floating algae matts are a risk to human health and recreation like boating and fishing, and businesses in the area, suffer along with the health of our beloved river.”
Those collaborative efforts to reduce the runoff are picking up steam. For example, conservation districts and land-owners are working together to fix gullies eroding farm fields, cities are upgrading or building new wastewater treatment plants, and communities are installing rain gardens.
But as the photo above illustrates, we still have work to do.
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That’s disgusting. It is precisely because of this impairment that the absurd scope of the new St. Croix Crossing was opposed. The bridge will increase the concrete runnoff surface and the inclusion of heavy metals in the impairment soup. It will cause runnoff to be warmed up both directly on the concrete and in the holding ponds that serve to hold sediment. This runoff impact of a bridge too large is exactly what the Wild and Scenic Rivers Act was designed to prevent. In addition, the bridge will likely stimulate damaging sprawl type development in Wisconsin which will further diminish runnoff quality into Lake St. Croix.