The federal Clean Water Act requires that states identify water bodies that do not meet water quality standards and that the states develop plans to restore these impaired waters. The restoration plans include an assessment of what pollutant is causing the impairment and how much of that pollutant the water body can handle and still meet water quality standards. This assessment is known as a total maximum daily load study, or TMDL. A common type of lake impairment affects the lake's ability to support aquatic recreation, which includes swimming, boating, and simply aesthetic enjoyment. This aquatic recreation impairment is due to excessive nutrients, most commonly phosphorus. While phosphorus is a nutrient that is needed for plant growth, excessive inputs can lead to high amounts of algae. This algae can impair recreational activities through unsightly algae blooms, which at times can include toxic forms of algae and unpleasant odors. Ten lakes within the Carnelian-Marine-St. Croix Watershed District (CMSCWD) are on this list of impaired waters: East Boot, Fish, Goose, Hay, Jellum's, Long, Loon, Louise, Mud, and South Twin (see Table 1 for impairment listing information). This TMDL report addresses these impairments and includes an evaluation of the ecological health of each lake, an assessment of the phosphorus sources to each lake, and guidelines on how to restore the aquatic recreational use of each lake. Summaries of these lake evaluations can be found on the CMSCWD's website (http://cmscwd.org/).
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Minnesota Pollution Control Agency (St. Paul, Minnesota)
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Minnesota Pollution Control Agency