Impaired waters

The Minnesota Pollution Control Agency is working on putting together an updated list of impaired waters, or bodies of water that do not meet their designated uses because of water quality standard violations. 

Waters impact almost every aspect of life in Minnesota. If a lake, river or stream has been polluted, it could be unhealthy for recreation, drinking water, food sources such as wild rice and fish, native species and more. Here are five things to know about impaired water, why it’s important and what individuals can do about it. 

1. What does “impaired waters” mean?

The Minnesota Pollution Control Agency reports that a body of water is impaired “if it fails to meet one or more water quality standards. Minnesota water quality standards protect lakes, rivers, streams and wetlands by defining how much of a pollutant such as bacteria or nutrients can be in water before it is no longer drinkable, swimmable, fishable or usable in other designated ways (called “beneficial uses”). Waters that do not meet their designated uses because of water quality standard violations are impaired. These standards are a long list of what is and is not allowed in water.”

Common impairments include: 

  • Mercury, which can lead to fish consumption limits

  • Nutrients from fertilizers and other sources that grow algae 

  • Sediment that clouds the water 

  • Bacteria that makes the body of water unsafe for recreational use

  • Unhealthy conditions for fish, bugs and other animals

Impairments in bodies of water are measured using total maximum daily loads. 

2. What is a total maximum daily load?

A total maximum daily load is required by the Clean Water Act for every impaired water. The EPA defines it as “the calculation of the maximum amount of a pollutant allowed to enter a waterbody so that the waterbody will meet and continue to meet water quality standards for that particular pollutant. A total maximum daily load determines a pollutant reduction target and allocates load reductions necessary to the source(s) of the pollutant.” In other words, these loads are a way to measure the pollutant(s) in a body of water to ensure that it is at a healthy state. 

The EPA lists the five steps that go into developing a total maximum daily load: 

  1. Determine the pollutant(s) to consider

  2. Estimate the body’s assimilative capacity 

  3. Estimate the pollutants every the waterway and the sources 

  4. Analyze the current pollutant load and determine if reductions are needed 

  5. Allocate the allowable pollutant load to ensure that water quality standards are met. 

3. Why is this in the news now? 

On Monday, Nov. 8, the Minnesota Pollution Control agency announced that 305 bodies of water and 417 impairments were added to the proposed 2022 impaired waters list. This brought the total of water bodies to 2,904 and impairments to 6,168. 

Some of the impairments found were PFAS, or perfluorinated alkylated substances, the “forever chemical.” 

The MPA says the chemical “used in numerous industrial processes and found in many consumer products, continues to be found in new water bodies throughout Minnesota. Perfluorooctane sulfonic acid (PFOS), a PFAS compound, can accumulate to levels of concern in fish and is transferred to humans when consumed, potentially causing adverse health effects.”

The Federal Clean Water Act mandates that states update impaired waters lists every two years. 

4. Are there local impaired waters? 

Unfortunately, yes. The proposed 2022 impaired waters list includes Lake Pepin for nutrients. Other local impairments include: 

  • Wells Creek: The creek has suspended solids. The Minnesota Stormwater Manual explains, “Solids originate from many sources including the erosion of pervious surfaces and dust, litter and other particles deposited on impervious surfaces from human activities and the atmosphere. Erosion at construction sites is a major source of solids.” E. coli has also been found in the creek. 

  • Bullard Creek: E. coli has been found in the creek. 

  • Cannon River: Nutrients and E. coli. 

  • Zumbro River: E. coli 

5. What can we do? 

The EPA reports that “engaging local communities and individual citizens is essential to any waterbody restoration effort.”

There are a variety of ways that people can work for the restoration and protection of waterways. These include getting to know the local waterway(s) and participating in total maximum daily load development processes. 

Public comments are currently being sought for Minnesota’s draft impaired waters list. A public information meeting is scheduled to discuss waterways in southeastern Minnesota. The bodies of water that will be discussed include the Cedar River Basin, Root River, Le Sueur River and the Mississippi River/Lake Pepin watersheds.

The virtual meeting will be at 1 p.m. on Wednesday, Dec. 15. It can be accessed at

  • Meeting number (access code): 2487 766 0492 

  • Meeting password: B95Eqw3QVPf

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