Characteristics of recently restored wetlands in the prairie pothole region

Between 1987 and 1991, 1892 prairie potholes were restored in northern Iowa, southern Minnesota, and southeastern South Dakota by state and federal agencies, most as part of the Conservation Reserve Program. The total area covered by these restored wetlands is approximately 2714 ha. Most restorations are small (less than 4 ha) wetlands with a seasonal hydrologic regime. Wetlands with an ephemeral/temporary water regime are under-represented compared to their pre-drainage extent. Information on basin morphometry, hydrology, and vegetation-zone development was collected on 62 wetlands restored in 1988. Earthen dams are installed on most (73%) restorations in the region, increasing the full pool volume but not the mean depth of the basin. Overall, restored wetlands have basin morphometries that are comparable to those of similarly sized natural wetlands. About 60% of the basins had their predicted hydrology or held water longer than predicted. Nevertheless, about 20% of the projects that we examined were hydrologic failures and either never flooded or had significant structural problems. Most restored wetlands had developed emergent and submersed aquatic vegetation zones, but only a few had developed wet prairie and sedge meadow vegetation zones.