Game Wardens with the Department of Natural Resources often focus on people breaking laws like hunting without a license, or boating while drunk.
But now they're engaged in a war to fight the spread of invasive species in our lakes and rivers.
There are many kinds of invasive plants and animals that D.N.R. wardens are worried about.
That's why for the next few weeks, wardens will be targeting boaters, to make sure they don't become ground zero, for an invasion.
This time of year, Game Warden Scott Thiede makes his living, keeping an eye on Wisconsin waterways.
But these days he's interested in more than just safe boating.
"It's highly important that folks realize that they are on the frontline of preventing the spread of invasive species in Wisconsin", Thiede said.
And this is what the D.N.R. Is worried about.
Eurasian Water Milfoil and Zebra Mussels could threaten lakes here in Western Wisconsin.
And those are just two invasive plants and animals that can change an entire ecosystem.
"They over take our lakes and make it difficult for recreationalists to maneuver through the lake, and it also interferes with the fish habitat", Lacey Hoyt with the DNR said.
And over the Fourth of July weekend, game wardens around the state will be inspecting boats for invasive hitch-hikers....and ticketing people for ignoring the law.
Game wardens and scientists say the best advice is to remember, don't transport water from lake to lake.
Also, either wash your boat off before hitting another hotspot, or let it dry for a few days between trips.
"They have a great impact on the waterways, the recreational use, the future of those waterways, and to the economy of Wisconsin", Thiede said.
And Thiede says the fight against invasive species doesn't stop when the summer boating season ends.
He reminds duck hunters that even during the winter, invasive species can be brought into lakes in other parts of the state.
He says, it's just a matter of paying attention.