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305b Assessments of lake conditions in Minnesota's major river basins

Lake assessments are prepared for the U.S. Congress under Section 305b of the Clean Water Act to:

  • estimate the extent to which Minnesota waterbodies meet the goals of the Clean Water Act, and
  • share this information with planners, citizens and other partners in basin planning and watershed management activities.

These assessments are a fundamental part of MPCA's state water quality management program.

Lakes are assessed for the swimmable goal of the Clean Water Act. Categories of assessments for supporting swimming use are:

  • fully supporting (FS)
  • partially supporting (PS)
  • not supporting (NS)

To view assessments of specific lakes, use the Lake Water Quality Assessment Program Data Search.

To view assessments of lakes, select the major river basin from the list of files shown below. Within each major river basin table, lakes are grouped by major watershed. These assessments are based on data collected through 2004.

Basins in Minnesota

basin2n.gif - 18.95 K

PDF Document Map - Minnesota Ecoregions and Hydrologic Basins (ecobasin)


Basin reports

Lake assessments

Based on the 2012 Minnesota Integrated Report to Congress of the United States (July 2013)

 

Figure 1. Carlson's Trophic State Index

Table 1 provides the Trophic State Thresholds used for determining use support for lakes. Actual detail of the assessment process for 303(d) and 305(b) may be found in the 2004 Minnesota Water Quality Surface Water Section report.

Table 1. Trophic Status Thresholds for Determination of Use Support for Lakes
(Carlson's TSI noted for each threshold. Taken from guidance manual.)

Table 1. Trophic Status Thresholds for Determination of Use Support for Lakes. (Carlson's TSI Noted for Each Threshold.). Taken from guidance manual.

Thirty-four years of data (1970-2004) were used in the assessments. Lakes sampled within the last 10 years are reported as "Monitored", compared with "Evaluated" when assessments are based on monitoring data more than 10 years old. All data are stored in the U.S. Environmental Protection Agency (EPA) "STORET" data system.

Lakes for which no monitoring data were available may have been assessed using a survey of local resource managers, as described below.

Map shapefiles

If you have any questions or comments, please contact Jen Crea at 651-757-2294.

  • ZIP Archive Assessed waters (2012) External Link
    Map shapefiles which represent the Minnesota 2012 assessments (per Section 305(b) Clean Water Act), including lakes, streams, and wetlands. These files were created for those interested in preparing computerized maps of the 305(b) assessments. To use these files you will need Geographic Information System (GIS) computer software. The zipped file contains shapefiles for use support (aquatic recreation, aquatic life, and aquatic consumption). The projection for the shapefiles is UTM extended zone 15, NAD83. The shapefile was created by the Minnesota Pollution Control Agency using the 1:24,000 scale National Hydrography Dataset.
  • ZIP Archive Archive - Assessed waters (2010) External Link
    Archive: Map shapefiles which represents the Minnesota 2010 assessments (per Section 305(b) Clean Water Act), including lakes, streams, and wetlands. These files were created for those interested in preparing computerized maps of the 305(b) assessments. To use these files you will need Geographic Information System (GIS) computer software. The zipped file contains shapefiles for use support (aquatic recreation, aquatic life, and aquatic consumption). The projection for the shapefiles is UTM extended zone 15, NAD83. The shapefile was created by the Minnesota Pollution Control Agency using the 1:24,000 scale National Hydrography Dataset.


More information

For more information about the 305b assessments of lake conditions in Minnesota's major watersheds, contact Steve Heiskary at 651-757-2419.

  • HTML Content Clean Water Act - Section 305b External Link
    The National Water Quality Inventory Report to Congress (305(b) report) is the primary vehicle for informing Congress and the public about general water quality conditions in the United States. This document characterizes our water quality, identifies widespread water quality problems of national significance, and describes various programs implemented to restore and protect our waters. (U.S. EPA)
Last modified on September 16, 2013 13:54