In 2009, road crews in Polk County, Wisconsin, began using leftover cheese brine to pre-wet road salt. Tests found the mixture helped salt stick to the road and cut salt use by 30 to 40 percent, while the dairy supplying the brine saved money it had been spending to dispose of it.

In a rural county in northwestern Wisconsin, a highway worker looked at a dairy’s waste and saw a road treatment.

A cheese plant making mozzarella and provolone was producing salty wastewater and paying to have it hauled away. Meanwhile, a county road crew was buying rock salt and losing some of it off the pavement before it could do much good.

That was the beginning of Polk County’s cheese-brine project, which entered full use in 2009. The arrangement later ended when its local dairy supplier closed. But the idea continued elsewhere: Green County, in southern Wisconsin, was still using cheese-production brine according to its 2024–2025 report.

Two waste problems that suggested one solution

The cheese brine in this story was a used saltwater solution from the cheesemaking process. It was already full of salt, which is exactly what road crews use to help melt ice.

Emil Norby, a Polk County highway employee, saw a possible connection between the dairy’s disposal headache and the county’s wasted road salt. As he told Modern Farmer, “I knew we had a lot of dairies looking to get rid of this stuff.” The brine came from F&A Dairy in nearby Dresser.

The method is called pre-wetting. Instead of spreading dry crystals, crews coat the rock salt in liquid to reduce the amount that bounces or is scattered off the road. According to a University of Wisconsin–Madison account of the project, two Wisconsin Department of Natural Resources employees helped the dairy and Polk County secure approval and develop application rates. The first season of full use was in 2009.

What Polk County reported saving

Outside the Beltway, summarizing contemporary coverage, reported that Polk County officials said they used 30 percent less road salt than usual in the first year. That fits the intended benefit of pre-wetting: if less salt is scattered away, less may be needed.

The money moved on both sides. Polk County saved $40,000 in its first season of full use in 2009. Modern Farmer also reported that F&A saved nearly $30,000 in brine-disposal costs. Chuck Engdahl, the dairy’s wastewater manager, summed it up as “Everybody wins.”

From a cost standpoint, it is easy to see the appeal. Whether the practice also reduces environmental harm depends on how much salt and other material ultimately reaches the surrounding water.

To give a sense of scale, NPR reported in January 2014 that Polk County had used at least 150,000 gallons of cheese brine over the preceding years. Norby said 38,000 gallons had been applied the previous winter alone.

Why Polk County stopped

The catch was the same thing that helped make the arrangement work: proximity.

A cheap byproduct can become expensive once hauling and storage are included. In February 2024, Wisconsin Public Radio reported that Polk and Burnett counties had stopped using cheese brine when their local cheese factory closed.

In the same interview, Green County highway commissioner Chris Narveson explained that the economics depend on how far crews must travel to collect the brine. Trucks, storage tanks, and suitable facilities also have to be available. The material’s low cost at the dairy is only part of the calculation.

Green County continued using it

Green County is a separate case. The Green County Water Quality Coalition’s 2024–2025 report, published through UW–Madison Extension, confirms that its highway department continued using brine from cheese production. The coalition credits the practice with reducing rock-salt applications and saving money.

Less rock salt still does not mean salt-free

Salt can pollute freshwater, so reducing its use matters. In a study announced by the U.S. Geological Survey in December 2014, researchers led by Steven Corsi examined chloride trends in urban streams and emphasized the need to “consider deicer management options that minimize the use of road salt while still maintaining safe conditions.” Across the study’s 30 monitoring sites on 19 streams, 29 percent of sites exceeded the EPA’s chronic aquatic-life criterion for chloride.

The scale of salt use helps explain the concern. Penn State Extension put annual U.S. road-salt use at roughly 20 million tons. Cheese brine does not eliminate the pollution problem: it contains dissolved salt too. Evaluating the environmental benefit therefore means counting the salt in both the brine and the rock salt, rather than looking only at how much dry salt a county buys.

Perhaps, the broader lesson is to look at what one operation pays to throw away and ask whether another nearby operation is paying to buy something that serves the same purpose.