Hey, I'm up here in the cheese state too. My outings on foot have pretty well been limited to the Ice Age Trail. Coming from out West, it's weird to adjust to the size of the parks here. On this trip, I doubt it would have been of much use, but for future trips that have better access to bodies of water, make sure to take a filter. That way, you don't need to lug the water around, you can just grab what you need when you need it. Really helps with pack weight, because water should pretty much be the densest thing you are carrying.
I have a filter! It's new to me, like everything else here. As I explore more outside of Wisconsin it's disappointing how little open space we have here. I suppose it's a consequence of fairly flat land. If it can be farmed, it is. The only backpacking, primitive camping I've found in Wisconsin is Black River State Forest, Kickapoo Valley Reserve around Lafarge and Northern Highland American Legion State Forest far up north. KVR has a fee, but I'm probably going to try it soon just to try something different. There are some options in the national forests up north, but I haven't figured out the rules or places to go yet. I first gave the filter a go at Donald County Park near Mount Horeb. A full loop is about six miles, and the last time I was there I did the outer loop and then a smaller inner loop for about eight miles. The Deer Creek runs through it, and I tried the pump out there. It seemed to work well. I haven't been yet this summer, but I also like Governor Dodge State Park. There's a fee to drive in, but the horse trail is 12-15 miles, depending on if you do the full loop or cut a little off. Still, it's nothing like getting into backcountry.