Lac qui Parle River Watershed Characterization Report

The Lac qui Parle River watershed, Hydrologic Unit Code (HUC) 07020003 covers 1,100 square miles of eastern South Dakota and western Minnesota. In 2015, intensive watershed assessment and monitoring began in the Minnesota portion of the watershed to characterize the health of the watershed. Like most southern Minnesota watersheds, the Lac qui Parle River watershed has seen drastic changes from prairies, wet prairies, lakes, and wetlands to a landscape used for commodity row crops and some urban development. Natural areas with rare features still exist, although at a much smaller range than prior to European settlement. Hydrologic changes have been well documented throughout southern Minnesota. Changes from perennial vegetation to cultivation, from multiple crops to mainly corn and soybeans, loss of surface storage through wetland draining, and channelization of natural streams are common throughout southern Minnesota, including the Lac qui Parle River watershed. At the same time, climate changes have occurred resulting in more rain and more flow annually. Hydrologic analyses showed a change in the relationship between rain and streamflow around 1984. Since 1984 all flow analyses have showed an increase, with the fall season showing the biggest changes. At the same time, permits for groundwater usage have increased and overall water use has remained steady to produce crops that have not been suitable for the Lac qui Parle River watershed until recent decades. Twenty-three fish barriers were found in the Lac qui Parle River watershed, mainly road retention structures on small streams. Only two biological monitoring sites were impacted by these barriers. Ongoing efforts are attempting to remove barriers to fish migration in other areas of the watershed, and future projects should consider the potential impacts to biological communities. Overall, streams in the Lac qui Parle River watershed have good riparian vegetation and have connection with their floodplain. These are important characteristics to preserve stream stability in areas where it still exists, and implement in areas where streams are unstable. Eight stream reaches were assessed for stream stability. Stability ratings showed one site in good condition, four sites in fair condition, and three sites in poor condition. Riparian vegetation communities have maintained the stability of most of the assessed reaches; however, historic incision and risk for future flooding could make these sites more unstable resulting in higher sediment loads and loss of habitat. The Lac qui Parle River watershed has numerous opportunities for restoration and protection. Historically channelized stream reaches provide great potential to restore a stream's meander pattern, lower its slope, create habitat, and create flood storage by reconnecting the channel with its floodplain. Thousands of historic wetlands exist throughout the watershed. Storage of precipitation in these areas will provide flood relief with an ever changing climate. Areas with rare and natural features should be protected as many of these areas can easily be disturbed and provide habitat to numerous threatened and endangered species within the watershed.