Fish and aquatic bugs are at risk in many lakes and streams across Minnesota, according to the state’s draft 2016 list of impaired waters. The Minnesota Pollution Control Agency (MPCA) released the draft list on July 13. The list represents an assessment of how well lakes and streams support fishing, swimming, and other beneficial uses. Water bodies that fail to meet standards are considered impaired. This assessment is mandated by federal law and requires a cleanup study for each impaired water body.
The agency is proposing to add 304 stream sections and nine lakes to the list because they fail to support the number and quality of aquatic life — fish and bugs — that they should support, according to research. Restoring these fish and bug communities often means improving habitat conditions along with decreasing pollutants such as nutrients that cause algae and sediment that clouds the water. Extensive tile drainage for cropland also changes the movement of water and can hurt aquatic life.
Impaired waters summary
- Fish and bugs stressed: 158 new listings for fish and 155 for bugs, 435 total for fish and 455 total for bugs
- Nutrient pollutants: 87 new listings (41 streams and 46 lakes), 645 total
- Bacteria pollutants: 83 new listings, 617 total
- Mercury pollutants: 78 new listings, 1,670 total
- Dissolved oxygen stressor: 10 new listings, 132 total
- Sediment pollutants: 6 new listings, 370 total
- Other pollutants: 3 new listings, 215 total
- Chloride pollutants: 1 new listing, 47 total
- Nitrate pollutants: 1 new listing, 17 total
- Total: 582 new listings, 4,603 total impairments
- 41 sections of streams — most in southern Minnesota — fail meet new standards designed to prevent algae detrimental to aquatic life and recreation like fish and swimming. The MPCA examined available data for 3,100 river sections and found that 415 stream sections do meet the standard, 41 do not, and the rest need more data for a determination. Nutrient standards have been in place for lakes since 2008, and standards for rivers went into effect in 2014. The agency may list more rivers as impaired by nutrients in future years as it further analyzes their potential to grow algae.
- 83 water bodies, including 2 areas of Lake Superior with beaches, have bacteria levels too high to meet standards. Bacteria can make water unsuitable for swimming and other recreation. Sources of bacteria include manure runoff, livestock in streams, and failing sewer systems.
- 78 water bodies have mercury levels in fish tissue or in the water that are too high to meet standards. Mercury can be toxic to humans and that’s why the state of Minnesota issues consumption advisories for fish. The largest sources of mercury in Minnesota’s environment come from air emissions like coal burning and taconite. About 90% of the mercury deposited on Minnesota comes from other states and countries.
In all, the number of impaired Minnesota waters on the draft 2016 list totals 4,603, with 582 new listings.
Coming off the list
The agency is proposing to remove two lakes from the impaired waters list because of changes in their surrounding watersheds:
- Lake Shaokatan in western Minnesota where addressing feedlot runoff, farming and urban sources of pollutants, and failing septic systems have resulted in all-time phosphorus lows for the lake and other improvements. The MPCA continues to monitor the lake to see if the low nutrient and algae levels become the new norm for Lake Shaokatan.
- Red Rock Lake, a small shallow lake in Hennepin County, where the agency will determine if recent pollutant reductions are sustainable enough to keep the lake meeting standards.
Removing those two lakes would bring the total number of water bodies delisted because of restorative action to 37. The agency is also looking to remove 68 impairments from the list because of corrections to water quality data or other reviews of information. The continued increase in impaired waters with few being restored highlights two points:
- Restoring waters takes a great deal of work by many people over a long time. It usually takes decades for waters to become impaired and restoration is a long-term commitment.
- Minnesota is detecting more waters in trouble because of its 10-year plan to study all 80 major watersheds in the state, funded by the Clean Water, Land and Legacy Amendment. The MPCA has started this study in all but a few watersheds.
For more information
Visit the MPCA's impaired waters page.
What we are assessing
MPCA scientists study the stone fly and caddis fly larvae on an empty mussel shell collected in the Des Moines River in southwest Minnesota. The larvae and mussels are indicators — similar to symptoms — of the river’s health. Scientists found many empty mussel shells in the river, suggesting the Des Moines River is not doing as well as it could. The MPCA is proposing to add the Des Moines River from Windom to Jackson to the 2016 impaired waters list because of nutrient levels and their impact to aquatic life. Several stretches of the river and its tributaries are impaired by nutrient levels, mercury, bacteria, ammonia and/or other conditions.
MPCA scientists study the aquatic insects and fish in the Des Moines River as indicators — similar to symptoms — of the river’s health. The MPCA is proposing to add the Des Moines River from the Windom dam to the Jackson dam to the 2016 impaired waters list because of nutrient levels and their impact to aquatic life. Several stretches of the river and its tributaries are impaired by nutrient levels, mercury, bacteria, ammonia and/or other conditions.
A field along the Minnesota River in the Mankato area lacks a wide enough buffer strip of deep-rooted plants and trees to help hold soil in place and filter out pollutants. The MPCA is proposing to add more than 100 sections of the Minnesota River or its tributaries in the Mankato area to the 2016 list of impaired waters. Several streams and parts of the Minnesota River in the Mankato area are impaired by nutrient levels that impact aquatic life, along with mercury and PCBs in fish tissue, bacteria, turbidity, and/or other conditions. More information on biological monitoring, including videos, can be found on the agency's Biological monitoring webpage.