The Big Eau Pleine Reservoir has gotten bad

The water looks like green paint during the latter period of summer at Big Eau Pleine County Park

Big Eau Pleine County Park

The county’s conversationists recently tested the beach at the Big Eau Pleine Reservoir, thanks to some grant money from the Wisconsin Department of Natural Resources.

But it wouldn’t take a scientist to see the problem. One look at photos of test bottles county conservationists shared with county leaders last week leaves no doubt what is wrong: The bottles are bright green. They look like they’d been dipped in a can of green paint, not a body of water connected to the county park that drives the highest revenue for the county.

That’s a problem.

A water sample from Big Eau Pleine County Park’s beach.

The county now has red warning signs on the beach at Big Eau Pleine Park, which has campgrounds as well as mountain biking trails, horse riding trails and disc golf among other amenities. Those signs warn of the beach not being safe.

Waterways green with algae are more than just an eye-sore. They rob the waterway of oxygen, which in winter especially can kill fish populations. Big Eau Pleine has had several major fish kills in the last few decades.

That excessive algae growth comes from excess manure from farmland. County leaders say Marathon County has the most intense farming in the entire country. Excess runoff from manure into the watershed that drains to the Big Eau Pleine adds excess nutrients to the water, which spurs algae blooms.

It also has an economic impact, with fewer people willing to fish or rent the campgrounds because of it.

Why is this happening? Biological oxygen load or BOD into the Big Eau Pleine was 14 times greater than the load into the city of Wausau’s Wastewater Treatment Plant.

County conservationists practically begged county leaders to spur them to action. “We know how to fix it,” says county conservationist Kirstie Heidenriech. “We just need to be willing to take the next steps.”

At least week’s meeting, the committee acknowledged the problem but took no action. But here are some of the suggestions county conservationists have for fixing the problem.

Steps to fix the BEP pollution problem

There are two big solutions Heidenreich suggested for making a major impact on the Big Eau Pleine reservoir.

• Reduce winter manure spreading: CAFOs — dairy farms larger than 1,000 animals — are already banned from spreading manure in the winter. They’re regulated by the state. Smaller farms are regulated by the county. Heidenriech’s suggestion is to prohibit manure spreading by farms with 300-999 cows. That could be paired with a program that helps farmers share equipment that injects manure into the soil directly, which greatly reduces runoff. This would have a huge impact, she says, because runoff in the winter is nearly three times that of spreading in the summer.