The Minnesota Wetland Conservation Act (WCA) was first passed in 1991. Rules were promulgated by the Minnesota Board of Water and Soil Resources (BWSR). The WCA mandates that wetlands must not be drained or filled unless (a) drain or fill activity is exempt or (b) wetlands are replaced by restoring or creating wetland areas of at least equal public value. The goal is no net loss of wetlands.
A wetland is defined by the presence of (a) hydric (developed under wet conditions) soils, (b) surface or subsurface hydrology (properties and distribution of water) , and (c) hydrophytic (affinity for water) vegetation. The Wetland Conservation Act applies to all Minnesota wetlands, except those identified on the DNR inventory of protected waters and wetlands. These wetlands are regulated by the DNR.