Lower St. Croix River

Watershed at a Glance

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.

Hydrologic Unit Code:07030005
Intensive monitoring start year:2009
Major lakesMajor rivers and streams
Forest, Sunrise Pools, Rush, Green, Big Marine, Coon
Rock Creek, Rush Creek, Goose Creek, Sunrise River, Lawrence Creek, Brown's Creek, Valley Branch, Trout Brook


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. 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

        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. Currently there are three TMDLs that have been completed in this watershed: Brown’s Creek Biota and Turbidity TMDL, Comfort Lake Forest Lake Watershed District 6 Lake TMDL, and the North Branch of the Sunrise River Bacteria TMDL. While these are complete, there are also others that started last year: Lake St. Croix TMDL, Sunrise River Watershed TMDL, Typo and Martin lake TMDL, Carnelian-Marine St. Croix Watershed District 10 Lake TMDL, and the Chisago Chain of Lakes TMDL.

        This watershed does not have one distinct river, and also has the watershed organizations in the south, which makes it easier to  address impairments ion 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.

        Monitoring and assessment reports and data

        Implementation plans

        What is a watershed?

        Illustration showing contour of land directing flow of water

        Learn the basics of a watershed.

        Chisago County SWCD


        Twin Cities Metropolitan Area watersheds

        There are 33 watershed districts (WD) and watershed management organizations (WMO) in the Twin Cities Metro Area. These metro watersheds are in 8 major (8-digit) watersheds: the Rum River, Lower St. Croix, Mississippi River (Twin Cities), Mississippi River (Lake Pepin), Minnesota River (Shakopee), South Fork Crow River, North Fork Crow River, and Cannon River watersheds. These WDs/WMOs are formed and regulated by MN Rules Chapter 8410.

        A number of Total Maximum Daily Load (TMDL) Studies and Implementation Plans have already been completed or are underway for impaired waters in metro watersheds. Moving forward TMDL studies will be done in conjunction with watershed restoration and protection strategies (WRAPS) reports, which will contain the needed implementation strategy elements. Metro WRAPS will follow the timing and guidance of the watershed approach, but note that these will be completed at the metro WD/WMO scale.

        MPCA staff also review metro watershed management plans that are developed by watershed districts and watershed management organizations.


        A list of MPCA staff contacts by metro watershed is available on the Twin Cities Metro watersheds page.