Lower St. Croix River

The Lower St. Croix watershed covers 585,735 acres and is located in northwest Wisconsin and east-central Minnesota. It is unique in that every stream in this watershed flows directly into the St. Croix River or Lake St. Croix. The drainage area contributes to the river’s lower 52 miles from Taylor Falls and St. Croix Falls to the convergence of the St. Croix and Mississippi rivers at Prescott, Wisconsin. Major cities are Stillwater, North Branch and Afton. This watershed is made up of watershed districts and watershed management organizations in the south and county management organizations in the north.

Land use in the watershed is predominately agricultural. However, development pressure is steadily increasing as the Twin Cities metropolitan area continues to sprawl to the north in Minnesota and to the west in Wisconsin. These land uses contribute to concerns about surface water quality, groundwater quality and quantity, as well as stormwater and wetland management.

    A handful of lakes and Lake St. Croix do not meet water quality standards for beneficial uses such as aquatic recreation and swimming. The main lake pollutant is phosphorus, causing algae blooms in summer months. This watershed does not have one distinct river, but smaller stream impairments range from biological fish and macroinvertebrate impairments and bacteria. The pollutants mainly reach the river and lakes through the urban and rural runoff.

        What's being done

        Monitoring and assessment

        There has been quite a bit of research and monitoring in this watershed. The Watershed Districts and Watershed Management Organizations developed plans and rules to protect and enhance water quality in their watersheds. The counties also have plans to monitor and restore the waterbodies within their boundaries.

        The MPCA has conducted lake monitoring, including one sentinel lake, and connected with watershed organizations in the south, making it easier to address impairments on a sub-watershed level. In the next few years, the MPCA and local government will collect any final monitoring data that is needed in order to complete the restoration and protection plans.

        Implementation plans