Last weekend we visited [ Nitschke Mounds park ](https://www.co.dodge.wi.gov/departments/departments-e-m/land-resources-and- parks/parks-and-trails/nitschke-mounds-park) which has a number of interesting features but the one I have the most questions about is the spring-fed pond .
The pond was open (not frozen) and there appears to be living algae or some other sort of aquatic plants, both somewhat uncommon for a small pond during the winter in Wisconsin.
There also is a residue on the rocks that perhaps indicates salts or other minerals in the water?
I’ve been trying to find out what is known about the chemistry of the pond but so far I haven’t had much luck. If you know more about this place please get in touch.