I went to Johnson Park in the mid-afternoon after a fresh snowfall and walked into the unmarked snow along the river. I walked about an hour, down and back, watching the ducks come up off the water as I got too close to them.
Going back to the car, I found that some kids had arrived and were sledding on the hills in the eastern part of the park.
There's plenty of parking. No admission charges. It's just a neat place to spend an afternoon.