Winter manure spreading ordinance possible

WIEN, Wis. — Protecting the natural resources of Wisconsin is a concern shared by many, dairy farmers included. For many years, residents of Marathon County have struggled with the health of the Big Eau Pleine Watershed, which encompasses a vast portion of the western half of the county.

Concerned stakeholders met Feb. 19 in Wien to learn about a proposed ordinance to regulate winter spreading of liquid and slurry manure, which would completely ban the practice in February and March. This would be in an effort to limit the amount of phosphorous entering surface water due to runoff.

“We all want and need clean water in our county to survive, no matter what industry we are in,” said Marathon County conservationist Kirstie Heidenreich. “The reason we focus so much on phosphorous is because it greatly impairs the quality of surface water.”

According to Heidenreich, 1 pound of phosphorous in surface water can create up to 500 pounds of algae, which plagues the water held in the Big Eau Pleine Reservoir.

“We estimate that between 500,000-750,000 pounds of phosphorous are going through the Big Eau Pleine River into the reservoir every year,” Heidenreich said. “We see the effects of that with phosphorous levels on the western side of the county that are about 3-4 times the state standard. In 2023, we had two samples that were 55 times the state standard.”

Finding the root of the problem is something Heidenreich said must happen now, before it is too late.

“Most of the surface water in western Marathon County is considered to be 303(d) phosphorous impaired by the Environmental Protection Agency,” Heidenreich said. “What that means is that we are teetering on the point where that body of water may no longer be able to sustain any type of aquatic life — it will have reached the point of no return.”

Heidenreich implored those in attendance — primarily farmers who will be affected by the ordinance — to work together with county leadership to find ways to prevent runoff from reaching the surface waters throughout the western half of the county.

“It’s very alarming to see those numbers,” Heidenreich said. “It’s very disheartening, we can work to do better, together.”

Together with her colleague, conservation analyst Matt Repking, Heidenreich said the idea of a proposed ordinance restricting winter spreading of manure is in the early stages of discussion.

“We wanted to engage in dialogue with the important stakeholders in Marathon County as we’ve begun to explore ways to improve our surface water quality,” she said. “We are looking for ideas to move the needle on surface water quality, with manure management.”

Heidenreich said they are seeking input from those stakeholders in the county who are impacted by the surface water issues. The ideas that are being brought together come from different management plans developed over the past 20 years.

“There is nothing proposed that is a new idea — nothing that hasn’t already been proposed in this county,” Heidenreich said. “We don’t have any type of ordinance ready to share, there isn’t even a draft form yet.”

Heidenreich said the months of February and March have been identified as the greatest runoff risk by Discovery Farms, the basis for the idea of banning spreading of liquid and slurry manure during those months. Spreading of solid, stackable manure would still be allowed.

Repking said stipulations would need to be in place for emergency applications.

Marathon County is home to farms of all sizes, some of which are already working with restrictions. In 2024, there were 348 dairy farms in Marathon County. Of these, 198 have manure storage facilities, while 150 farms haul manure daily, with no storage.

“When it comes to runoff, it really doesn’t matter where the manure comes from, what size the farm is,” Repking said. “What matters more is how it is being managed.”

Fourteen Marathon County farms are considered concentrated animal feeding operations, which are already limited by restrictions for winter spreading as part of their nutrient management plans and have manure storage. An additional 18 farms are considered livestock siting farms, all having at least 160 days of storage.

Out of the 150 daily-haul farms, 22 have nutrient management plans submitted.

“Using those farms as a sub-sample, the herds range from 25 to 180 cows, with an average of 77 cows,” Repking said. “About 41% of that sub-sample produce liquid or dairy manure. If a winter spreading ban were put in place, it would affect at least 62 farms in Marathon County — they would have to figure out a solution for their manure for those two months.”

Farms without nutrient management plans would be required to obtain winter spreading permits, working with conservationists and agronomists to identify fields that are low-risk for runoff, outside of the spreading ban in February and March. Repking said the hope would be to encourage all those farmers to develop nutrient management plans.

Repking estimated a 25-cow herd would need storage of 50,000 gallons of manure for 60 days while a 180-cow farm would need about 350,000 gallons of storage.

If a winter spreading ban is put in place, Repking said part of the proposal is to create a line of communication for implementation.

“It would take 3-5 years for it to essentially go into effect,” Repking said. “That is to give farmers enough time to work out solutions or invest in some type of manure storage.”

Heidenreich encouraged attendees to look at the potential benefits of a spreading ban.

“How much phosphorus could we reduce if we can get everyone to come together for 60 days, to reduce runoff in our highest risk months?” Heidenreich said. “Looking at the daily-haul farms, it would be almost 16,000 pounds of phosphorous that we would be keeping out of our surface water. That isn’t counting other farms that have storage but still spread manure during that time because it is perfectly legal to do so right now. That bare-bones reduction is still a colossal reduction."