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Water Quality Standards

Water quality standards are fundamental tools that help protect Minnesota’s abundant and valuable water resources from pollution. Minnesota adopted its first statewide water quality standards in 1967. Some of these first standards are unchanged and just as pertinent today; others have been updated. Many new standards and significant new regulations have been added since 1967. As reflected in the federal Water Pollution Control Act Amendments of 1972, better known as the Clean Water Act, states are required to review their water quality standards every three years and adopt standards that meet minimum national requirements, including addressing additional pollutants that may threaten beneficial uses. Minnesota’s water quality standards meet or exceed federal requirements.

This Web page provides basic information about Minnesota’s water quality standards, including what they are, the uses they protect, where they come from, and how to access and use water quality standards in Minnesota rules.

Introduction

Water quality standards include the following components:

• Beneficial uses – designation of the public uses and benefits our water resources provide to people.
• Numeric standards – allowable concentrations of specific pollutants in water, established to protect the beneficial uses.
• Narrative standards – descriptions or statements of unacceptable conditions in and on the water.
• Nondegradation – extra protection for high-quality or unique waters to keep them from being degraded.

Water Quality Rules

Water quality standards and related provisions are found in several Minnesota rules.

Minnesota Rules Chapter 7050. This is the primary rule for statewide water quality standards.  It includes:

• A classification system of designated beneficial uses for both surface and ground waters,
• Numeric and narrative water quality standards,
• Nondegradation provisions,
• Provisions for the protection of wetlands, and
• Other provisions related to water quality standards and the protection of Minnesota’s water resources from pollution.

Minnesota Rules Chapter 7052. This rule contains water quality standards, nondegradation provisions, and methods for setting water quality-based effluent limits for point sources (explained under “How standards are used”). Minnesota R. ch. 7052 is applicable only to waters in the Lake Superior basin. This rule, called the Great Lakes Initiative (GLI), was mandated by an amendment to the federal Clean Water Act in 1987. The GLI rules provide a common approach across state lines for the control and minimization of the discharge of persistent and bioaccumulative pollutants into the Great Lakes system. All eight states bordering the Great Lakes have adopted the GLI.

Minnesota Rules Chapter 7053. This is a new rule established in 2008 to include the items listed below, which were previously in Minn. R. ch. 7050.

• Minimum treatment requirements and effluent limits for wastewater discharges,
• Phosphorus effluent limits,
• Effluent limits needed to meet water quality standards,
• Requirements for aquaculture facilities, and
• Other provisions related to point source discharges.

Minnesota has other rules that deal with water-related issues; for example, there are separate rules for:

• Permitting the discharge of treated wastewater,
• Permit fees,
• Feedlots,
• On-site sewage treatment systems, and
• Ground water standards.

Minnesota water quality rules are available on the Office of the Revisor of Statutes Web page. The rules also can be accessed from the “Rules/Regulations” option on the MPCA’s home Web page.

• Chapter 7050. Water Quality Standards for Protection of Waters of the State
• Chapter 7052. Lake Superior Basin Water Standards
• Chapter 7053. Effluent Limits and Treatment Requirements for Discharges to Waters of the State 
• For information on status of revisions to  portions of Minn. R. chs. 7050 and 7052 see the sidebar for links to additional Web pages.

This Web page focuses on the water quality standards in Minn. R. ch. 7050.

Beneficial Uses

“Beneficial uses” are the uses that water resources and their associated aquatic communities provide for people; the U.S. Environmental Protection Agency (EPA), which administers the Clean Water Act, uses a related term “designated uses”. Seven beneficial uses, designated Class 1 through 7, are defined in Minn. R. 7050.0140. These uses are listed below. The numbers 1–7 are not intended to imply a priority ranking to the uses.

• Drinking water – Class 1
• Aquatic life and recreation – Class 2 (sometimes shortened to “fishing and swimming”) 
• Industrial use and cooling – Class 3
• Agricultural use, irrigation – Class 4A
• Agricultural use, livestock and wildlife watering – Class 4B
• Aesthetics and navigation – Class 5
• Other uses – Class 6
• Limited Resource Value Waters – Class 7

Ground water. In practice, underground waters are protected for just one use, as an actual or potential source of drinking water. All ground water is designated as Class 1.

Surface water. All surface waters, lakes, rivers, streams and wetlands, in Minnesota are protected for multiple uses. The vast majority of surface waters are designated as Class 2; that is, they are protected for aquatic life and recreation. A relatively small number (about 150 reaches) are designated as limited resource value waters (Class 7). Both Class 2 and Class 7 waters (i.e., all surface waters) are also protected for industrial use (Class 3), agricultural uses (Class 4A and 4B), aesthetics and navigation (Class 5), and other uses (Class 6). In addition, some surface waters are protected as a source of drinking water (Class 1). Examples of Class 1 waters include trout streams, Lake Superior, portions of the Mississippi River upstream of St. Anthony Falls, the Red River of the North, and some mine-pit lakes. 

As mentioned, the vast majority of surface waters in Minnesota are fully protected for aquatic life and recreation. This is consistent with the national interim goal in the Clean Water Act that all waters should have “quality which provides for the protection and propagation of fish, shellfish, and wildlife and provides recreation in and on the water,” wherever attainable.  This is often times shortened to the phrase “fishable and swimmable”.

Limited resource value waters are protected for a very limited aquatic community and limited recreational use. Every Class 7 waterbody is individually assessed by the MPCA, and the change from Class 2 to 7 is proposed as a rule change providing the public an opportunity to comment. Most Class 7 waters are headwater streams or channelized ditches that provide poor aquatic habitat due to channel alterations and low flows. Class 7 reaches range from less than one to about 20 miles in length, and all together make up less than one percent of Minnesota’s 92,000 miles of rivers and streams. Essentially all Class 7 reaches receive treated wastewater from a point-source discharge.

Subclasses. Use classes 1, 2, 3 and 4 are divided into two or more subclasses. Of these, the Class 2 subclasses are the ones most people should be familiar with; they are listed below:

• 2A Cold-water fisheries, trout waters, also protected as a source of drinking water
• 2Bd Cool- and warm-water fisheries, also protected as a source of drinking water
• 2B Cool- and warm-water fisheries (not protected for drinking water)
• 2C Indigenous fish and associated aquatic community (not protected for drinking water)
• 2D Wetlands (not protected for drinking water)

Tiered Aquatic Life Use Framework. The MPCA has initiated research to transition to a Tiered Aquatic Life Use (TALU) Framework for aquatic life beneficial uses. The fact sheet gives additional details about TALU and a likely timeframe for integrating it into Minnesota's water quality rules. Additional discussion on the TALU Framework can be found on the TALU Web page.

How to Determine the Uses a Particular Waterbody is Protected for

To know which water quality standards apply to a particular waterbody, the designated beneficial use classifications must be known. In particular, it is important to know whether it is a Class 7, and if not, which Class 2 subclass the waterbody is, and whether it has a Class 1, or special nondegradation designation.

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 for major waters in major surface water drainage basins, and
• Minn. R. 7050.0430 Unlisted waters (also Minn. R. 7050.0425, which deals with unlisted wetlands).

Listed waters. Minnesota R. 7050.0470 specifically lists certain surface waters and some of their assigned use classes. Only waters assigned uses outside the normal or “default” uses are listed individually in Minn. R. 7050.0470. For example, surface waters protected for drinking, trout waters, Class 7 waters, and outstanding resource value waters (see “Nondegradation”) are listed. 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). This fact confuses some people when they can’t find their waterbody of interest listed in Minn. R. 7050.0470.

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. Below are two examples of listings found in Minn. R. 7050.0470 (Note, T., R., and S. mean Township, Range, and Section):

• Trout water (Class 1B, 2A, 3B, etc.)
• Whitewater River, Main Branch, (T.107, R.10, S.2, 3, 9, 10; T.108, R.10, S.1, 2, 10, 11, 14, 15, 22, 23, 26, 27, 35): 1B, 2A, 3B;
• Non-trout water protected for drinking (Class 1C, 2Bd, 3C, etc.)
• Red River of the North, (Breckenridge to Canadian border): 1C, 2Bd, 3C;

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 (or Minn. R. 7050.0425 for wetlands) applies. This short but very important part of the rule classifies all unlisted waters (except wetlands) as Class 2B plus the other uses. It is quoted below in its entirety:

7050.0430 UNLISTED WATERS
All surface waters of the state that are not listed in part 7050.0470 and that are not wetlands as defined in part 7050.0186, subpart 1a, are hereby classified as Class 2B, 3C, 4A, 4B, 5, and 6 waters.

To emphasize, all surface waters in Minnesota not specifically listed in Minn. R. 7050.0470 are Class 2 waters, protected for aquatic life and recreation.

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). MPCA staff is working on an application that will display the use classifications for all waters of the state in an interactive map format.

Numeric and Narrative Standards

Numeric standards. Numeric water quality standards represent safe concentrations in water that protect a specific beneficial use. If the standard is not exceeded, the use should be protected. Minnesota R. ch. 7050 has numeric standards designed to protect drinking water, aquatic life and recreation, industrial, agricultural, aesthetic and wetland uses, and limited resource value waters.

Numeric standards are listed in two places in Minn. R. ch. 7050. First, all the numeric standards applicable to four common categories of surface waters are listed in Minn. R. 7050.0220. For example, all the standards applicable to trout waters, and their associated uses (including the drinking water standards), are listed together. This reminds readers that surface waters are protected for multiple uses and that some pollutants have more than one applicable standard. In such cases the most restrictive standard applies.

The second place numeric standards are listed is by individual use class and subclass in Minn. R. 7050.0221 – 7050.0227.

In general, the numeric standards used most often to protect surface waters are the Class 2 aquatic life and recreation standards. With few exceptions, if the Class 2 standards are met, other uses such as industrial or agricultural uses are protected as well. Chronic standards provide protection for human health and the aquatic community; because of the similar foundation for developing Class 2 human health protection and federal drinking water standards, generally, Class 2 chronic standards are as restrictive as the concentration needed to protect drinking water supplies, depending on the pollutant.

Waters designated for drinking, both surface and ground, are protected for this use by the federal Environmental Protection Agency (EPA) drinking water standards (see Web links). Drinking water standards are found in Minn. R. 7050.0220 and 7050.0221.

The Minnesota Department of Heath has adopted separate drinking water standards called Health Risk Limits (HRL). HRLs are most often applied to ground water (see Web links).

Because the roughly 70 Class 2 numeric standards are the ones most often used, further description of them is helpful. Most Class 2 standards for toxic chemicals have three parts, defined as follows (see table):

• Chronic standard (CS). The highest concentration of a toxicant to which aquatic organisms can be exposed indefinitely with no harmful effects, or to which humans or wildlife consumers of aquatic organisms can be exposed for a lifetime with no harmful effects.
• Maximum standard (MS). A concentration that protects aquatic organisms from potential lethal effects of a short-term “spike” in toxicant concentrations. The MS is always equal to one half the final acute value.
• Final acute value (FAV). The concentration that would kill about half of the exposed individuals of a very sensitive aquatic species. The FAV is most often used as an “end-of-pipe” effluent limit to prevent an acutely toxic condition in the effluent or the mixing zone.

Class 2 chronic standards for toxic chemicals are reviewed for three aspects of aquatic life and consumption protection (see table):

• Toxicity-based. The chronic standard is based on the direct toxicity of the toxicant to fish and other aquatic organisms. Maximum standards and final acute values are always toxicity-based.
• Human health-based. The chronic standard is based on protecting people who eat fish from Minnesota waters and drink the water (if the surface water is also protected for drinking).
• Wildlife-based. The chronic standard is based on the protection of wildlife species that eat aquatic organisms.

Numeric Aquatic Life and Recreation Standards – Class 2

*The mixing zone is the part of a river or stream that receives a point-source discharge, where the effluent is mixed and diluted by the flowing water, and where chronic standards can be exceeded.

Normally the MPCA calculates both a toxicity-based and human health-based value and adopts the more restrictive of the two as the standard for that pollutant. Wildlife-based standards based on consumption of aquatic life are available only for four pollutants (DDT, dioxin, mercury and PCBs). They were developed by EPA for the Great Lakes Initiative and adopted into Minn. R. ch. 7052 (Minn. R. ch. 7050 has no comparable wildlife-based standards).

Narrative standards. A narrative water quality standard is a statement that prohibits unacceptable conditions in or upon the water, such as floating solids, scums, visible oil film, or nuisance algae blooms. Narrative standards are sometimes called “free froms” because they help keep surface waters free from visible and basic types of water pollution. The association between a narrative standard and beneficial use is less well defined than it is for numeric standards; however, most narrative standards protect aquatic life, recreation, or aesthetic beneficial uses. Because narrative standards are not quantitative, determining that one has been exceeded typically requires a “weight of evidence” approach to data analysis showing a pattern of violations.

Nondegradation

MPCA initiated revisions to the nondegradation portions of Minn. R. ch. 7050 in January 2007, see sidebar link for more information.

A third element of water quality standards in addition to beneficial uses and numeric or narrative standards is nondegradation (equivalent to the federal term “antidegradation”). The fundamental concept of nondegradation is simple – waterbodies with water quality better than applicable standards should be maintained at that existing high quality and not allowed to be degraded. Nondegradation protection is a very important aspect of pollution control, because protecting high quality waters not only means that future generations will have these highly valued recreational and aesthetic resources to enjoy (think of the St. Croix River, for example), 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.

Federal regulations establish three levels or tiers of nondegradation, which are the approach states are to use when adopting nondegradation rules.

• Tier I – At a minimum waters should be in compliance with water quality standards, and existing and attainable beneficial uses should be protected.
• Tier II – Provides protection to waters whose water quality is better than standards so the existing high quality is maintained, unless there is a social and economic need to degrade the waters down to the level of the standards.
• Tier III – Provides the highest level of protection from pollution to waters specifically identified as very high quality, important recreational resources, ecologically sensitive or unique.

Nondegradation Tiers I and II are covered in Minn. R. 7050.0185. Tier III is covered in Minn. R. 7050.0180. Consistent with Tier III regulations, the MPCA has designated a number of waters as outstanding resource value waters (ORVW). These waters deserve extra protection for a variety of reasons. ORVWs include, for example, all the waters in the Boundary Waters Canoe Area Wilderness and Voyagers National Park, Lake Superior, natural lake trout lakes, and wild and scenic and recreational river segments such as the St. Croix, Rum, and portions of the upper Mississippi and Cannon Rivers. In addition, ecologically unique waters in state scientific and natural areas and a unique wetland type called calcareous fens have been designated as ORVWs.

New or expanded point-source discharges are prohibited to the most pristine or sensitive ORVWs. These are the “prohibited” category of ORVWs. For other ORVWs, new or expanded point sources are prohibited unless the discharger can demonstrate there is no “prudent or feasible” alternative to allowing the increased pollutant loading. These are the “restricted” category of ORVWs. ORVWs are located throughout the state.

Additionally, in the Lake Superior basin only, all surface waters are designated as outstanding international resource waters (OIRW), except waters that are already in the more protective ORVW category or have been reclassified as Class 7 waters. This designation was adopted as part of the Great Lakes Initiative rule (Minn. R. 7052.0300 – 7052.0330). Implementation of nondegradation for OIRW waters focuses on reducing the loading of bioaccumulative pollutants to the Lake Superior basin because of the sensitivity of the Lake Superior ecosystem to these pollutants.

Where Standards Come from

People often ask, “Where do water quality standards come from?” Most of Minnesota’s aquatic life (Class 2) standards are based on EPA guidance. The Clean Water Act requires EPA to develop and publish aquatic life criteria (see Web links). EPA criteria are concentrations of pollutants that if not exceeded will protect aquatic life, fish consumption, and recreation. States must adopt the EPA criteria into state rules before they have the legal status of a water quality standard.

States can adopt a value more stringent than the EPA criterion as the MPCA did in the case of mercury. Or states can adopt a value more lenient than the EPA criterion (as the MPCA did in the case of ammonia) if the state can show that the standard is “as protective as” the EPA criterion based on local information. If EPA has not developed a criterion for a particular pollutant and there is a need for a standard, the MPCA can and has developed standards using our own expertise.  Examples are standards in Minn. R. ch. 7050 for the herbicides atrazine, alachlor, acetochlor, and metolachlor.

Unlike aquatic life criteria EPA adopts Class 1 drinking water standards into federal rules through the federal rulemaking process. Thus drinking water standards are legal entities that the MPCA simply incorporates into Minn. R. ch. 7050 by reference.

How Standards are Used

Numeric and narrative water quality standards have a variety of functions; they are used to:

1. Define maximum allowable levels of pollutants to protect beneficial uses,
2. Ascertain the quality of the state’s water resources by comparing the standards to monitoring data,
3. Identify waters that are polluted,
4. Help establish priorities for the allocation of treatment resources and cleanup efforts,
5. Set effluent limits and treatment requirements for dischargers in some situations, and
6. Assess risks to surface water from  ground water contamination sites and help define cleanup goals.

A highly visible function of water quality standards is the assessment of water quality conditions statewide and the identification of waters that do not meet water quality standards. The Clean Water Act requires this activity and the MPCA publishes a list of impaired waters every two years (see Web links for impaired waters).

Variances

The MPCA may grant variances to the water quality standards in Minnesota Rules Chapter 7050 and the effluent discharge restrictions in Chapter 7053.  The MPCA must list the variances granted under these two rules by October 1 of each year.  The following table identifies the variances in National Pollutant Discharge Elimination System/State Disposal System (NPDES/SDS) permits issued by the MPCA as of October 1, 2009.  The table includes the facility granted the variance, the rule from which the variance was granted, the water affected, the year granted, and any restrictions that apply in lieu of the rule requirements.

Active Variances from Minnesota Rules Chapters 7050 and 7053

MPCA Contacts on Water Quality Standards

The following MPCA staff can answer questions and provide additional information on water quality standards.

General:

Mark Tomasek (Supervisor)
651-757-2788
mark.tomasek@state.mn.us

Gerald Blaha
651-757-2234
gerald.blaha@state.mn.us

Pesticides and Toxic Pollutants:

Angela Preimesberger
651-757-2656
angela.preimesberger@state.mn.us

Phil Monson 
651-757-2580
phil.monson@state.mn.us

Nondegradation:

Bill Cole
651-757-2281
william.cole@state.mn.us

Rule Process and Revisions:

Carol Nankivel (Nondegradation)
651-757-2597
carol.nankivel@state.mn.us

William Wilde (Triennial Water Quality Standards Amendments)
651-757-2825
william.wilde@state.mn.us

Site-specific Standards:

Howard Markus
651-757-2551
howard.markus@state.mn.us

Variances:
Katrina Kessler
651-757-2490
katrina.kessler@state.mn.us

All these contacts can be reached at:

Minnesota Pollution Control Agency
520 Lafayette Road N.
St. Paul, MN 55155
Toll-free: 800-657-3864 or TTY 651-282-5332

Links to Related Web Sites

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 Ground Water
• 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
• Minnesota Water Quality Standards: Physical Alterations to Wetlands
• Tiered Aquatic Life Uses - (TALU)