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Lower St. Croix River

Father and daughter sitting on end of dock looking at lake. A white boat is tied to the side of the dock.

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 issues include biological fish and macroinvertebrate impairments and bacteria. The pollutants mainly reach the river and lakes through the urban and rural runoff.

Monitoring and assessment

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.

Strategy development for restoration and protection

See all approved TMDLs in the Lower St. Croix River Watershed:


Eric Alms
Watershed project manager