It’s been a bad summer for Madison-area lakes.
The Yahara River between lakes Mendota and Monona last month became a dead zone after green scum covered the surface. Heavy and frequent rain washed huge amounts of soil, manure and other phosphorus-laden material into the water, triggering the largest bloom of blue-green algae on Lake Mendota since 1994, according to the UW-Madison Center for Limnology. And when the algae dies and decomposes, it reduces oxygen in the water, killing fish.
Some of the stinky muck has dissipated and is being removed. But five public beaches on lakes Mendota, Monona and Waubesa remained closed Tuesday because of blue-green algae that can sicken swimmers.
Similarly, blue-green algae and dead weeds lowered oxygen levels on Indian Lake in western Dane County last week, killing thousands of fish, according to the state Department of Natural Resources.
It might be tempting to dismiss and blame this summer’s foul lake conditions on unusual weather patterns. But scientists predict a warming climate will produce more chaotic storms. So the threat of torrential rain isn’t going away.
“What this points out is the lakes are very fragile,” says James Tye, executive director of the Clean Lakes Alliance. “And with the increase of rain events that will continue as climate change becomes more and more predominant in our environment, we in our community are going to have to double-down on our efforts.”
The Clean Lakes Alliance is a diverse group of policymakers, business leaders, farmers, scientists and citizens working to cut in half the amount of weed-feeding phosphorus that reaches our lakes. So far, they’re nearly a third of the way to that goal.
Farmers are adopting better storage practices for manure and injecting it into the ground rather than spreading it on the tops of fields where it can wash away.
Municipalities are trying to keep leaves and lawn waste out of streets, monitoring construction sites for erosion, and slowing and filtering stormwater of organic material.
More city residents are creating rain gardens and volunteering to restore wetlands and clean shoreline.
So much is at stake.
Madison’s lakes define and promote our community as a great place to live and work. They provide recreation, relaxation and beauty.
The effort to improve their health must continue — and expand — so this summer’s green shorelines, closed beaches and large fish kills become a thing of the past.