Water quality standards
Water has always been important to Minnesota and is a key part of our history, culture, economy and recreation. There are more than 13.1 million acres of lakes, rivers, streams and wetlands. In order to protect this vital resource, the MPCA monitors water quality, sets water quality standards and regulates what may go into the water.
Water Quality Standards are used to:
- Protect beneficial uses, such as healthy fish, bugs, and plant communities, swimming and other water recreation, and fish consumption
- Evaluate water monitoring data used to assess the quality of the state’s water resources, and
- Identify waters that are polluted or impaired or in need of additional protection
- Set effluent limits and treatment requirements for discharge permits and cleanup activities
The federal Clean Water Act requires states to designate beneficial uses for all waters and develop water quality standards to protect each use. Water quality standards include the following:
- Beneficial uses — identification of how people, aquatic communities and wildlife use our waters.
- Numeric standards — allowable concentrations of specific pollutants in a water body, established to protect the beneficial uses.
- Narrative standards — statements of unacceptable conditions in and on the water.
- Non-degradation — extra protection for high-quality or unique waters and existing uses.
Explicit in the Clean Water Act was the presumption that a water body should attain healthy aquatic life and recreation uses unless proven otherwise. Minnesota's rules provide a framework that includes broad uses for those, and also the following additional uses: drinking water (domestic consumption), industry, agriculture, navigation and aesthetic enjoyment. Waters not meeting the minimal aquatic life uses are called “limited resource value waters” and may have modified standards, but are still protected.
The MPCA adopts Water Quality Standards into two Minnesota rules (Chapters 7050, Waters of the State, and 7052, Lake Superior Basin Water Standards). The details of and process for reviewing all aspects of water quality standards is described in more detail below.
The term “water quality standard” is also sometimes used more broadly to include minimum wastewater treatment requirements, effluent limits for point-source (large stationary facilities) dischargers, and other additional provisions and requirements in the state’s water quality rules. Minn. R. ch. 7053, State Waters Discharge Restrictions, and parts of Minn. R. ch. 7052, contain the details of how water quality standards are implemented in point-source discharge permitting.
The MPCA currently has a number of active Water Quality Standards projects. More information is available through each project page, or by referring to the Public Rulemaking Docket.
- Use Classifications, Human Health Methods, and Standards for River Eutrophication/Total Suspended Solids/Chloride
- Sulfate standard to protect wild rice
- Nondegradation rulemaking
- Tiered Aquatic Life Use (TALU) Framework
Water Quality Standards (WQS) review and prioritization occurs every three years in a public process. Rulemaking (to address the priority standards) occurs as the standards are ready for adoption (i.e., technical work done, implementation sorted out, SONAR ready, etc.). As a result there could be multiple rulemaking projects underway at any given time. Citizens, stakeholders and affected parties can count on a public review and discussion of the state’s WQS every three years, which helps provide the foundation for future water quality standards.
The MPCA’s decision to conduct rulemaking to amend the WQS is based on information from several sources. The federal Clean Water Act requires that state water quality standards be publicly reviewed on a three year cycle. This “triennial review” identifies many aspects of the water quality standards that then become the subject of rulemaking. Other rulemaking efforts to amend the water quality standards are initiated by legislative direction, public petitions or legal directives, or by the MPCA’s identification of a problem or deficiency. In addition to the effect on the biological communities and the environment, changes to the water quality standards can affect the wide range of people, including local government, industries, agriculture, recreation and all the people who use Minnesota’s waters.
Elements of Standards
Water quality standards are the fundamental regulatory and policy foundation to preserve and restore the quality of all waters of the state. They consist of three elements:
- Classifying waters with designated beneficial uses;
- Narrative and numeric standards to protect those uses; and
- Nondegradation (antidegradation) policies to maintain and protect existing uses and high quality waters.
In Minnesota’s water quality standards, all groundwater is protected as a source of drinking water (Class 1.) All surface waters are classified and protected for multiple beneficial uses. These uses encompass the benefits and uses of surface waters as listed in Minn. R. ch. 7050 and summarized below. Note: The use class numbers 1-7 are not intended to imply a priority rank to the uses.
Aquatic life and recreation
Agricultural and wildlife
Aesthetics and navigation
Limited Resource Value Water (LRVW)
Minnesota adopted a framework that includes broad uses for domestic consumption, aquatic life, recreation, industry, agriculture, navigation and aesthetic enjoyment. Groundwater has one beneficial use, domestic consumption. Surface waters have multiple beneficial uses that are reflected in the standards. Waters determined not to attain aquatic life and recreational uses are reclassified as “limited resource value waters,” and have modified standards, but are still protective for downstream waters and other beneficial uses.
A narrative water quality standard is a statement that prohibits unacceptable conditions in or upon the water. Narrative standards that address very fundamental and basic forms of water pollution, such as floating solids, scums, visible oil film, or nuisance algae blooms are also referred to as “free froms”. Whereas, other narrative standards set water quality goals for more defined pollutants to protect surface waters and aquatic biota from:
- Impairment of the biological community, and
- Impairment of fish for human consumption.
A numeric standard is the concentration of a pollutant in water intended to achieve the beneficial use. Numeric standards reflect specific beneficial uses as adopted by the use classes (1-5). If not exceeded, numeric standards will protect the beneficial use. Numeric standards are not available for all pollutants and so are complemented through additional tools including, biological monitoring, to fully assess the beneficial use of aquatic community health. If a pollutant has numeric standards for more than one beneficial use class, the most stringent value applies.
Nondegradation or maintaining all waters in an unpolluted and natural state is the State’s policy goal. Nondegradation protection is a very important aspect of pollution control, because protecting water quality not only means that future generations will have highly valued recreational and aesthetic resources to enjoy, but because preventing the degradation of surface waters is usually a lot less costly to society than trying to restore them once they have become degraded.
Nondegradation or federal antidegradation regulations provide three tiers (levels) of protection for surface waters.
- Tier one requires that at a minimum, existing uses be maintained and protected for all waters. (Minn. R.7050.0185)
- Tier two requires high water quality (water quality better than the applicable standard) be maintained unless a lowering of water quality is necessary to accommodate important economic and social development (Minn. R. 7050.0185).
- Tier three provides the highest level of protection for specific waters designated as outstanding, very sensitive or unique resources (Minn. R. 7050.0180). In Minnesota, these special waters are called outstanding resource value waters (ORVWs). There are two categories of ORVWs, ‘prohibited’ and ‘restricted’. New or expanded discharges are strictly prohibited to the first category. Examples of ‘prohibited’ ORVWs include waters within the Boundary Waters Canoe Area Wilderness and Voyagers National Park. New or expanded dischargers are prohibited to the restricted category unless the discharger can demonstrate there is no ‘prudent or feasible alternative’ to allowing the increased pollutant loading. Examples of ‘restricted’ ORVWs include portions of Lake Superior and federal and state designated scenic and recreational river segments such as the St. Croix River. In addition to designated ORVWs, which are located statewide, all surface waters in the Lake Superior basin are designated as Outstanding International Resource Waters (OIRW) (Minn. R. 7052.0300). Implementation of nondegradation for OIRW waters focuses on reducing the loading of bio-accumulative pollutants to the Lake Superior basin.
How to determine the uses a particular waterbody is protected for
To know which water quality standards apply to a particular waterbody, the beneficial use classifications must be known.
Two parts of Minn. R. ch. 7050 are important for determining the beneficial uses assigned to any water of the state; they are:
- Minn. R. 7050.0470 Classifications or listings for major waters in major surface water drainage basins, and
- Minn. R. 7050.0430 Unlisted waters (also Minn. R. 7050.0425, classifies unlisted wetlands).
All surface waters are protected for aquatic life and recreation (Class 2), unless the waterbody has been individually assessed and re-classified, through rulemaking, as a limited resource value water (Class 7). Both Class 2 and Class 7 waters (i.e., all surface waters of the state) are also designated Class 3, 4A, 4B, 5 and 6, and are protected for the associated beneficial uses, as listed above (Minn. R. 7050.0400 to 7050.0470).
Listed waters. Minnesota R. 7050.0470 is a listing, by major watershed, of individual waters and their associated use classifications. Only a limited subset of all waters is listed in Minn. R. 7050.0470. For example, waters that are individually listed include trout waters, surface waters protected for drinking, outstanding resource value waters, and Class 7 limited resource value waters. Minnesota R. 7050.0410 and 7050.0420 state the additional uses that all listed waters are protected for. It should be noted that the vast majority of surface waters are not listed (see “Unlisted waters,” below).
The listings in 7050.0470 are arranged by nine major Minnesota watersheds; rivers and streams are listed first, followed by lakes and wetlands, both in alphabetical order.
Unlisted waters. If the water of interest is not listed in Minn. R. 7050.0470, and again, most surface waters are not, then Minn. R. 7050.0430 applies. This short but very important part of the rule classifies all unlisted waters with multiple beneficial uses. These “unlisted” surface waters of the state are classified as Class 2B, 3C, 4A, 4B, 5, and 6 waters.
For wetlands, information on their classification is found in (or Minn. R. 7050.0425. They are specifically listed as for wetlands)(Class 2D, 3D, 4C, 5, and 6) waters.
Occasionally waters may go by more than one name. If in doubt about the classification of a waterbody of interest we suggest you consult MPCA staff (see list of contacts).
The following web pages provide more information on topics related to water quality standards.
- U.S. EPA Water Quality Criteria
- U.S. EPA Water Quality Standards: guidance, laws, and strategies
- U.S. EPA Drinking Water and Health Advisories
- Minnesota Department of Health, Health Risk Limits for Groundwater
- MPCA Streams and Rivers
- MPCA Lakes
- MPCA Groundwater
- MPCA Environmental Data Access
- MPCA Impaired Waters List and TMDL Process
- MPCA Guidance Manual for Assessing the Quality of Minnesota Surface Waters
- MPCA Proposed Water Quality Standards Revision
- MPCA Wastewater
- Minnesota Wetlands Water Quality Standards
- Physical Alterations to Wetlands
- Tiered Aquatic Life Uses - (TALU)
MPCA contacts on water quality standards and rulemaking
- Mark Tomasek (Supervisor,651-757-2788, firstname.lastname@example.org
- Use classifications
- Gerald Blaha, 651-757-2234, email@example.com
- Pesticides and toxic pollutants
- Bill Cole, 651-757-2281, firstname.lastname@example.org
- Rule process and revisions
- Carol Nankivel (Nondegradation), 651-757-2597, email@example.com
- Site-specific standards
- Howard Markus, 651-757-2551, firstname.lastname@example.org
- Tiered aquatic life uses
- Will Bouchard, 651-757-2333, email@example.com
MPCA published a Public Notice in March 2009 identifying eight major water quality standards topics in need of revision. Of these topics some (1, 2, 4, 6, 7-Class 3 only, and 8) are part of a rule revision project. Updated information on this active project is found on the Planned Amendments to Water Quality Standards page. The remaining topics will be part of a future rule revision expected to begin in 2014.
- Addition of eutrophication standards for river systems;
- Modification of the existing turbidity standards;
- Additions or revisions of numeric WQSs for protection of aquatic life based on U. S. Environmental Protection Agency (EPA) 304(a) Ambient Water Quality Criteria for cadmium, copper, and nonylphenol (note: MPCA is not planning to adopt the diazinon criteria as part of this rulemaking);
- Re-evaluate the aquatic life standard for chloride;
- MPCA-derived Class 2 WQSs for nitrate based on aquatic life toxicity;
- Updates to human health-based WQSs needed to maintain consistency with the Minnesota Department of Health’s Health Risk Limits in Minn. R. ch. 4717 and EPA’s Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000);
- Re-evaluate and update existing Class 3 (Industrial Consumption) and Class 4 (Agriculture and Wildlife) water use standards;
- Potential water use classification changes for specific water bodies, including new Class 1 designations on certain reaches of Thief River, updating Class 2A trout waters, and reviewing and adding Class 7 limited resources value waters; and
- Minor administrative changes.
Draft Technical Support Documents
A key part of proposing new or revised WQSs is developing the technical foundation behind the narrative and numeric WQSs. MPCA develops this foundation based on review of scientific data, consideration of relevant rules, guidance, public comments, and consultation with topic experts at the U.S. Environmental Protection Agency (administrator of the CWA), other state agencies, Tribal Authorities, and academic researchers. The product of this review are topic-specific Technical Support Documents (TSDs) that will later be introduced in the rulemaking record as the supporting documents (exhibits) to the proposed rules and Statement of Need and Reasonableness (SONAR). The goal of publishing these documents prior to the official notice for proposing revised rules and SONAR is to obtain early comments and additional data to help MPCA refine and improve the basis for the proposed water quality standards.
TSDs are available on the following topics (note: not all topics being revised as part of the scope of this review have TSDs available):
- Aquatic life-based WQSs for nonylphenol, cadimium and copper
- Aquatic Life Water Quality Standards Technical Support Document for Cadmium Draft October 14, 2010, revised September 2012
- Aquatic Life Water Quality Standards Technical Support Document for Copper Biotic Ligand Model Draft October 14, 2010
- Aquatic Life Water Quality Standards Technical Support Document for Nonylphenol and Ethoxylates Draft October 14, 2010
- Aquatic life-based WQSs for nitrate and supplemental fact sheet on strategy to reduce nitrogen loading
- Aquatic Life Water Quality Standards Technical Support Document for Nitrate Draft November 12, 2010
- Developing Surface Water Nitrate Standards and Strategies for Reducing Nitrogen Loading Draft November 12, 2010
- University of Minnesota report on the recommended changes to the Class 3 and 4 WQSs with a TSD summary on MPCA draft considerations for revsions