Native vegetation based on NRCS soils information shows approximately two thirds forest soils (light blue, green and dark green), less than 10% savanna soils (red and red with blue stripes) and about 20% prairie (yellow) and wet prairie (light yellow). Most of the city is heavily wooded, on moraine topography with many slopes and wetlands and three small private lakes – Hornbeam Lake, Horseshoe Lake, and the eponymous Sunfish Lake, which was formerly known as Lake Thereau by the early French settlers of the area. For new construction, the minimum lot size is of buildable land to keep with the city's goal of maintaining a rural atmosphere.