It was early in the morning at North Trout Lake Campground when Josh Stirn pulled into the boat launch with a large trailer being led by a large black truck.
The boat launch was quiet that day, only two empty trailers in the parking spaces. Stirn popped open a chair, took a seat and began waiting for boaters to leave the water.
His job is to stop them before they leave and ask if they want their boats decontaminated. That means spraying the boat with heated water to powerwash anything clinging to the boat away.
Stirn is a volunteer for the Vilas County boat decontamination program. Beginning in 2018, the program is a partnership between the county's land and water department and the University of Wisconsin-Oshkosh. They are specifically targeting the tiny spiny water flea, where it has found a home in several lakes in the Northwoods.
“You have to kind of have a trained eye to locate them and know what you're looking for," said Stirn. "They are definitely visible. You could see them on the side of your boat — or on your fishing line is where they like to hang out.”
Once an invasive species is introduced to an ecosystem, you can’t go back. So the tactics of protecting natural resources goes from prevention to containment, to ensure no other areas can be affected.
This can be seen in the Northwoods, as conservationists and local officials work to curb the spread of aquatic invasive species. The decon unit is a mobile unit that travels between four lakes known to have a population of the spiny water flea: Plum, Trout, Big Muskellunge and Star Lake each receive monthly visits during the season.
Equipped with a large water tank, heater and several attachments to reach different areas of the boat, Stirn goes through the different parts of the decon unit, showing off nozzles of different shapes and sizes. After firing up the decon unit, boats are essentially powerwashed to kill anything that could be hanging on.
“We have to have it at 120 [degrees] for sensitive areas and 140 [degrees] for anywhere else on the boat," said Stirn. "We fill up this water tank, and then it just comes through these hoses. And then we have a bunch of different attachments for the hoses.”
But because decontamination is voluntary, it’s not unusual for boaters in the Northwoods to turn Stirn and his colleagues down. According to data collected by volunteers out with the decon unit, roughly 13% of boats were decontaminated using the mobile unit in 2025.
The power wash method is pretty standard throughout the country. But other methods are being used for greater efficiency.
Utah has been battling invasives such as quagga mussels and Eurasian water milfoil, and has been using large “baths” called dip tanks to decontaminate watercraft.
Similarly to Vilas County, Utah used to use a mobile, heated pressure washer unit to decontaminate boats.
The idea of the dip tank began with two boaters who enjoyed Lake Powell, a reservoir of the Colorado River along the Arizona-Utah border, but hated the lines and wait time to get their boats decontaminated.
They pitched the idea and began working with local and state authorities to develop the dip tank. Their company, Clean Wake LLC, claims to be able to decontaminate a boat in minutes, much less than the time needed to do so with a pressure washer.
They work by having a boat lowered into the tank. The driver starts the engine and lets it run to cycle heated water through its system, killing everything that may be lingering around.
The first dip tanks were installed about six years ago. Bruce Johnson, a lieutenant with Utah's aquatic invasive species enforcement program, says the dip tanks have continuously been tested and improved on since the program began.
“We have a complete filling of the watercraft, which we haven't been able to accomplish previously, as well as a complete 100% mortality of any villagers or live adults that may be inside of that boat in the internal systems, " said Johnson. "We have proven we've done our biological testing on our dip tanks, and we now can say scientifically we are 100% confident, 100% mortality.”
Now Utah is placing them in the ground as well as deploying mobile units.The state currently has five dip tanks with plans for two more to be installed
Both Utah andWisconsin have laws requiring some form of decontamination or inspection of boats and other watercraft used in their waters.
But Catherine Higley, a lake conservation specialist for Vilas County, says obstacles such as boater buy-in, infrastructure, cost and enforcement could pose issues that would make a dip tank program a little harder for Wisconsin to put into place.
Clear Wake holds a patent on the dip tank technology and is its only manufacturer. According to Johnson, dip tanks cost roughly $1 million to install, including construction, pump houses, filters and utility connections. This a price that may not be justifiable due to the concentration of lakes in the Northwoods.
“For example, like out west, there's just truly less places to access the water than there is here," said Higley. "There's just not the people power that I'm aware of to hit all of those places.”
Spiny water fleas are observed in42 lakes and rivers in the state according to the Wisconsin Department of Natural Resources. Constant reporting is also necessary to keep accurate data on the presence of the species.
Higley says some boat landings may not have the infrastructure for dip tanks, and installing it may disturb areas.
“If you're going to be installing things like that, it's got to be at really busy landings where there's already some of that infrastructure in place and enough room to do it.” Higley said.
Ultimately, Higley thinks more regulation and enforcement would be a good place to start in the Northwoods. She suggested something similar to what she experienced in Wyoming, which requires boats to check in at designated checkpoints.
"That could be something a little bit more feasible,” she said, “but I don't see that being something that people will do a lot unless there was regulation in place.”
Dip tanks may not be the right fit for northern Wisconsin, but they may be something to think about when looking for new solutions.
Maria Peralta-Arellano is a reporter covering water quality and the environment for WXPR and a Report for America corps member. Report for America recruits, places and supports talented journalists in local newsrooms across the United States. Make a tax-deductible donation to support her work and Report for America will match it dollar for dollar. Donate here.
