Tiered aquatic life use (TALU) framework
Minnesota is working to revise its water quality standards (Mn Rule Chapter 7050) to incorporate a tiered aquatic life use (TALU) framework for rivers and streams. The TALU framework represents a significant revision to the water quality standards of the state's aquatic life use classification. The framework builds upon existing water quality standards with a goal of improving how water resources 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 the state of Minnesota. Adoption of TALU will only affect Class 2 (Aquatic Life) and Class 7 standards.
The adoption of a Minnesota TALU framework achieves several goals:
- Biological standards: Incorporated into water quality standards, they provide a more direct method to measure and protect biological health and identify water quality problems that chemical measurements alone might miss.
- High quality water resources: TALU provides a mechanism to identify and protect high quality water resources.
- Modified or limited water resources: TALU provides a mechanism to classify and assess modified or limited water resources. These include channelized streams and ditches.
- Stressor identification: Improve our ability to accurately identify the wide diversity of stressors that impact Minnesota's water resources.
Achieving these goals through the TALU framework will bring Minnesota closer to protection and maintenance of the biological, chemical and physical integrity of water resources in the state.
Internal stakeholder meetings
External stakeholder meetings
Creation of stream classification
Development of biological condition gradient (BCG)
Index of Biotic Itegrity (IBI) development
External stakeholder meeting
Final draft of implementation recommendations report
Tiered aquatic life uses development (create beneficial uses and biocriteria for exceptional and modified rivers)
Impaired Waters Listing Process (guidance for UUas, use designation, assessment, etc.)
Draft rule language
Solicitation of public comments in State Register
Promulgation of proposed standards ai State Register
Pilot TALU-based assessment
Post hearing comment period and response
Receive ALJ report
MPCA Citizens' Board
EPA Region V approval
Start of TALU-based assessments and reporting
- Framework and Implementation Recommendations for Tiered Aquatic Life Uses (TALU) - new report
- A meeting and webcast was held on June 13, 2012 to provide an update on the development of a TALU framework for Minnesota. A webcast of the meetingis available (note: this link opens in a new browser window). The presentations given during the meeting are posted below.
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, which means they must be “fishable and swimmable.”
Traditionally, aquatic life has been protected through the application of water chemistry based standards. For example, the Minnesota's standard for dissolved oxygen in all non-coldwater streams is 5 parts per million (ppm). Such chemical criteria have served well and they will continue to be important in protecting Minnesota's aquatic resources.
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 will still miss others and can as a result be under and in some cases over protective of aquatic resources.
The TALU framework relies on a combination of biological, physical, and chemical monitoring to identify potential water quality issues. The TALU framework accounts for natural variation through appropriate water body classification and relies on an adequate bioassessment program to measure aquatic life directly. The bioassessment monitoring framework inherit in TALU is coupled with numeric biological standards which provide a direct measure of the beneficial use that is being protected.
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.
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 if it demonstrated that the biology cannot attain at least the General Use. Determination of use is based foremost on the biology which is currently based on an assessment of fish and invertebrates.
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 would need to be performed 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 then be redesignated Modified or Limited 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 from 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.
Figure 1. Biological condition gradient
Biological standards. Water quality standards in Minnesota are currently based on chemical and physical criteria such as dissolved oxygen and pH. These criteria 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 aspect of our protection measures. However, the addition of biological monitoring and biological standards will complement them and will result in refinement of chemical criteria.
Figure 2. Five major factors that determine the integrity of aquatic resourcesDiagram of the The Five Major Factors that Determine the Integrity of Aquatic Resources
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 nondegredation 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 under 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 are fully protective 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.
As part of the TALU implementation and adoption process, a number of meetings will be held with internal MPCA and external stakeholders. The goal of these meetings will be to inform stakeholders and to provide a forum for discussion and input that will improve the TALU framework. These discussions will improve our ability to smoothly incorporate TALU into existing MPCA programs. Below is information on past and upcoming meetings.
- MPCA internal stakeholder informational meeting (June 2008)
- External stakeholder informational meetings (January 2009)
- External stakeholder workgroup meetings (February 2009)
- MPCA internal workgroup TALU implementation meetings (February 2012)
- MPCA external stakeholder TALU implementation meetings (June 2012)
Additional meetings will be held when we begin the rulemarking process.
As part of internal and external engagement, the MPCA commissioned the development of a report with recommendations for the implementation of TALU in Minnesota. This report is now available below and the MPCA welcomes feedback. This report and feedback from stakeholders will provide the transition as we move into the rulemaking phase.
The rulemaking process is expected to begin in 2013.
- Webcast: Tiered Aquatic Life Uses (TALU)stakeholder meeting (June 2008)
- Biological Monitoring
- Impaired Waters
- Water Quality Standards
- Intensive Watershed Sampling
- U.S. EPA TALU workshop modules
- An overview of the development of TALU in Ohio
- Use of Biological Information to Better Define Designated Aquatic Life Uses in State and Tribal WQS: Tiered Aquatic Life Uses (EPA-822-R-05-001)
- Biological Condition Gradient
- The Biological Condition Gradient
- A Primer on Using Biological Assessment to Suport Water Quality Management