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Williow Creek, before and after the big July 7 influx of phosphorus

The influx of phosphorus can dramatically change the color of our waterways within days. Above are pictures from before an after a huge algae bloom turned Willow Creek from blue to slimy green June 7.

Within hours on July 7, the water on Lake Mendota went from summer blue to slimy green, thanks to the first major algae bloom of the season. As the State Journal reported, at least five Madison-area beaches were closed because of concerns over blue-green algae — and summer has barely even begun. For our lakes — and all of us who enjoy them — algae blooms do not have to be the norm.

Algae blooms in Wisconsin are the result of a potent cocktail: Phosphorus from agricultural fertilizers and manure, wastewater treatment plants, industrial facilities and even your lawn gets swept up into the lakes after a rain storm. Then algae explodes in abundance. A spell of warm weather following a big storm can cause blooms to be even worse.

For us on the shore, decomposing algae is smelly and noxious. But some algae also can cause serious illness and even be deadly to people or pets that come in contact with it. Public Health Madison and Dane County had to shut down the beaches to protect people from the impacts of this imminent health threat.

In June of 2017, the Yahara watershed was wracked with the worst algae bloom in 20 years. UW-Madison’s Center for Limnology documented the outbreak in harrowing fashion, showing just how costly — for habitats and taxpayers alike — these blooms can be.

This problem is statewide. According to the state Department of Natural Resources, 47 percent of the waterbodies on the state’s impaired waters list fail phosphorus pollution limits. With Wisconsin becoming warmer and wetter as the climate changes, the conditions that toxic algae species love increase. Correspondingly, so will the risk of more dangerous algae blooms.

To tackle this public health and environmental problem, we need to get rid of the “legacy phosphorus” that’s built up over decades in our rivers, lakes and streams and prevent more phosphorus from being added to them. Since 2010, Wisconsin’s innovative phosphorus rules have been a critical component of phosphorus pollution reduction efforts statewide. The rules give pollution sources — from farmers to wastewater treatment plants — choice and flexibility about how to most effectively and efficiently reduce phosphorus pollution.

In Dane County, these rules spurred a wide-ranging effort by the Madison Metropolitan Sewerage District to reduce phosphorus pollution. The Yahara Watershed Improvement Network and the ambitious projects they’ve undertaken, sometimes in partnership with local farms, are starting to make a difference in reducing the phosphorus entering our waters. And the “Suck the Muck” campaign launched by Dane County Executive Joe Parisi, in which phosphorus is removed from the bottom of streams, is starting to address the legacy phosphorus.

By reducing phosphorus — the organic material in manure, soil, leaves and other material that washes into our waterways — we can help keep our communities healthy, our beaches clean, and our tourism economy running.

When we think of summer, we should think of clear blue water, not beach closings and lakes and rivers covered in slime. We have the tools to fix the problem, and we need our state and local elected officials to commit to making sure Wisconsin’s lakes, rivers and streams are better off for our kids, and for their kids.

Know where your elected officials stand on preventing phosphorus pollutionand algae blooms from choking our beaches and threatening public health. Don’t accept beach closings, noxious scum and toxic blue-green water as the new normal.

Redsten is president and CEO of Clean Wisconsin: