Minnesota adopted changes to its water quality standards (Minn. Rule Chapters 7050 and 7052) that establish a tiered aquatic life uses (TALU) framework for rivers and streams. These rule amendments affect Class 2 (Aquatic Life) standards. The EPA approved the TALU framework rule in 2018.

The adopted TALU framework is a significant revision to the aquatic life use classification in the state's water quality standards. It built upon existing water quality standards to improve how water quality in streams and rivers are monitored and managed. Additionally, these changes advance the ability to identify stressors and develop effective mechanisms to improve and maintain the condition of waters in Minnesota.

The adopted TALU framework enhances the protection and maintenance of the biological, chemical and physical integrity of state water resources by achieving the following goals:

  • Establishes biological water quality standards. This provides a more direct method to measure and protect biological health and identify water quality problems that chemical measurements alone might miss.
  • Protects high-quality water resources. The framework provides a mechanism to identify and protect high quality water resources.
  • Provides a mechanism to appropriately and reasonably classify and assess modified water resources. These include channelized streams and ditches.
  • Improves stressor identification. This provides greater accuracy when assessing the stressors that impact Minnesota's water resources.


The MPCA published its notice of intention to adopt proposed rule amendments to state water quality standards (Minnesota Rules, Chapters 7050 and 7052), to establish a TALU framework and modify Class 2 Beneficial Use Designations, in the State Register on December 19, 2016, together with the proposed amendments.  During the 45-day comment period, which ended at 4:30 p.m. on February 2, 2017, the MPCA received more than 25 valid requests for a public hearing to be held on the proposed amendments.

The MPCA held a public hearing on Thursday, Feb. 16, 2017, in the MPCA St. Paul office, which was video-conferenced to regional offices in Duluth, Detroit Lakes and Marshall. Administrative Law Judge James R. Mortenson conducted the hearing. Following the hearing, a post-hearing comment and rebuttal comment period were held, during which additional written comments on the proposed amendments were submitted to the Office of Administrative Hearings (OAH). With the conclusion of the rebuttal comment period on March 24, 2017, the hearing record closed.

On April 24, 2017, Judge Mortenson issued his report. Within it, he concluded, in part, that: (a) the MPCA complied with the legal administrative rulemaking requirements; (b) there are no negative findings or defects in the proposed rule amendments; and (c) the amendments are necessary and reasonable. He also recommended that the proposed amendments be adopted. The judge's report is available below in the Procedural Rulemaking Documents section. Also available at this location are the exhibits introduced into the public hearing record and the comments submitted to the OAH during the post-hearing and rebuttal comment periods.

The MPCA adopted the rule amendments on September 21, 2017 (see Order Adopting in the Procedural Rulemaking Documents section below) and published its Notice of Adoption in the State Register on October 16, 2017. The rule amendments became effective five working days after the notice was published..

Procedural rulemaking documents


October 16, 2017

September 21, 2017

April 24, 2017

March 24, 2017

MPCA Rebuttal Response submitted to the OAH

Non-MPCA Rebuttal Response submitted to the OAH

March 17, 2017

MPCA Post Hearing Comments submitted to the OAH

Non-MPCA Post Hearing Comments submitted to the OAH

February 16, 2017

February 3, 2017

December 19, 2016

August 25, 2014

Beneficial use designations for stream reaches (water use classification tables identified in the proposed amendments)

See the Incorporations by reference page for the beneficial use designation tables. Scroll down to "7050.0470 Classifications for surface waters in major drainage basins."

Rulemaking schedule/public participation opportunities

Stage of rulemaking



Request for Comments

Request for Comments published August 25, 2014. Close of Comment period, October 17, 2014

Drafting of Rule Language/SONAR

November 2014 to November 2016

Pre-proposal Public Engagement Period

December 2015/September 2016

Public Informational Meeting on Draft Rule Amendments (held during MPCA Advisory Committee meeting)

June 21, 2016

Public Comment Period/Notice of Intent to Adopt Rules

45-day public comment period began on December 19, 2016, and will remain open until 4:30 p.m. on February 2, 2017.

Public Hearing

February 16, 2017

Post-Hearing Comment Period

Feb. 17, 2017, until 4:30 p.m on March 17, 2017.

Post-Hearing Rebuttal Period

March 18, 2017, until 4:30 p.m. on March 24, 2017.

Administrative Law Judge (ALJ) Review

April 24, 2017

Notice of Adoption published in State Register

October 16, 2017

U.S. EPA Review and Approval

June 26, 2018

Why does Minnesota need a tiered aquatic life use framework?

The Clean Water Act (CWA) requires states to assign beneficial uses to waterbodies and to develop water quality criteria to protect those uses. Most surface waters in Minnesota are protected for aquatic life and recreation. Traditionally, aquatic life has been protected through the application of water chemistry based standards. However, the use of only chemical and physical water quality standards to protect aquatic life may provide an incomplete assessment. Measuring one, two or even a handful of chemical and physical parameters as a surrogate for protection of aquatic life can miss impairments. The TALU framework relies on a combination of biological, physical, and chemical monitoring to measure the attainment of aquatic life goals directly. The TALU framework also produces a systematic process with a monitoring and assessment program that collects the right kinds of data which can be used at the same scale that management is being applied. As a result, monitoring and assessment work in parallel with water quality standards to develop effective standards that result in the protection of designated uses.

What is the TALU framework being considered?

The TALU framework will move Minnesota's aquatic life standards from a “one-size-fits-all” approach to one that protects appropriately classified waters based on their biological potential. This means that high quality or Exceptional Use waters will be given additional protection to ensure that the condition of these habitats are maintained. The majority of streams and rivers will continue to be protected as General Use or good quality waters. Some waters that are impacted by legacy or historical impacts (for example ditches) could be eligible for a lower goal if it is demonstrated that the biology cannot attain at least the General Use. Class 2 waters meeting Exceptional Use biological goals can be redesignated as an Exceptional Use because the biology has demonstrated that the use is attainable. Similarly, waters meeting the General Use goal would be designated General Use. However, if the General Use goals are not met, then additional analyses are used to determine the attainable use. Specifically, a Use Attainability Analysis (UAA) would need to be performed to determine if the habitat is limiting the biology and what is the cause of the poor habitat. Biological communities that are limited by habitat that are a result of legal activities (for example ditch maintenance) could be redesignated Modified Use.

Biological goals for TALU are based on a scientific model called the biological condition gradient (BCG) and reference waters. The BCG model describes how biological communities change with increasing levels of stress. The BCG is based on the concept that waterbodies receiving higher levels of stress have biological communities with lower condition compared to waterbodies receiving lower levels of stress (see Figure 1 below). The BCG provides a common framework to interpret changes in biological condition regardless of geography or water resource type. It permits a more accurate determination and classification of Minnesota's aquatic resources which improves the ability to make well-informed decisions on aquatic life designations. The BCG is supported by reference condition sites. These reference condition sites are waters that are minimally or least disturbed and therefore serve as a benchmark for assessment. Goals or biological criteria developed using both the BCG and reference sites largely agree and serve to strengthen these goals.

What are the major goals/outcomes of the TALU framework?

Biological standards. Water quality standards based on chemical and physical criteria, such as dissolved oxygen and pH, do not directly measure the health or condition of biological communities which include fishes, insects, mussels, aquatic plants and algae. Although chemical and physical measures can tell us a lot about water quality, these criteria are essentially surrogates for a direct measure of the biological community. This can be problematic due to the large number and diversity of the stressors that impact biological communities which include chemicals, reduced oxygen, sedimentation, increased temperature, and habitat degradation (see figure 2 below). As a result, the monitoring of chemical and physical parameters for all potential stressors can become too cumbersome to be practical. Rather than measuring the wide variety of stressors, biological communities can be monitored as they are a direct measure of the response of the biota to a wide range of physical and chemical stressors. In other words, their condition is a reflection of all the impacts of multiple stressors over time. Chemical standards have been, and will remain, an important tool for restoring and protecting beneficial uses. However, the addition of biological monitoring and biological standards will complement them and will result in refinement of chemical criteria.

High quality water resources. Another limitation of Minnesota's current water quality framework is that high quality resources are often under protected. At present there is a framework to protect the degradation of high quality waters called antidegradation, but there are still elements of Minnesota's antidegradation provisions in rule that can allow considerable degradation of these waters without violating the CWA. TALU establishes a higher tier of use to protect these high quality waters. Once a water body has been established as meeting the requirements of a high quality water resource, the resource needs to be protected to maintain that status. The concept of protecting the “existing” use of a waterbody is one of the most important tenets of the CWA.

Modified or limited water resources. There are water resources in this state that will not in the near future meet the CWA interim goals due to legacy impacts. These legacy impacts are those impacts that preceded the CWA. This includes streams under drainage maintenance or other irreversible hydromodification that preclude attainment of goals. For example, channelized streams and ditches would be included in this category. TALU provides a mechanism to monitor and set realistic expectations for waters that are unlikely to meet goals due to legacy impacts. The expectations fully protect the existing uses of each waterbody and recognize their historical and current site specific context. This element of TALU allows for the establishment of realistic expectations for waterbodies that have multiple and well established uses.

Stressor identification: When biological communities are determined to not be attaining General Use goals, the MPCA will need to have the tools and knowledge to determine in a timely manner if a lower use is appropriate and if the water body does not attain the designated use, what stressors are resulting in nonattainment. TALU incorporates the concept of pollution into assessments of condition and provides an opportunity to address the key stressors that are the most determinant of biological condition. In doing so, TALU allows assessment and water quality management efforts to focus on the correct problems.

Some other goals/benefits of TALU adoption include:

Monitoring of incremental improvements in water quality. This allows entities working to improve water quality to document and show progress toward a goal. TALU helps guide development and modification of water quality standards to produce improved standards. TALU merges the design and practice of monitoring and assessment with the development and implementation of water quality standards.

Technical support documents used to develop TALU framework

Technical support documents