In 1983 the Nature Conservancy purchased, and donated to the Field Station, 12 acres of acidic bog called the Sapa Spruce Bog and 11 acres of swamp hardwood.

This pristine bog adjacent to the Field Station is the southernmost black spruce bog in the state. It contains southern outliers of many plant species and represents a very different wetland community from that contained in the Cedarburg Bog. A plant species list for the Sapa Bog is available. Access to this bog is allowed for research purposes only.