Minnesotas impaired waters 101
A very brief history of the Clean Water Act
In response to concerns regarding the health and safety of our nations waters, the Federal Clean Water Act (CWA) was signed into law in 1972.
Created to protect the chemical, biological and physical integrity of our nations waters, the CWA and subsequent revisions made groundbreaking changes to the way our nation monitors and protects our waters.
Clean Water Act Section 303(d)
(Summarized in plain English)
- States must assess all waters and determine if they meet H2O quality standards.
- Waters that do not meet those standards must be added to the Impaired Waters List (the 303[d] list). The list is updated biannually.
- States must conduct TMDL studies in order to set pollutant reduction goals needed to restore the impaired waters.
Among these advancements, the CWA requires states and some Native American tribes to adopt specific water quality standards for all water bodies in their jurisdiction. If a particular body of water violates those standards, its considered polluted, and a US EPA-approved clean-up plan must be created.
Setting the standards
Minnesota adopted its first statewide water quality standards in 1967, and todays standards meet or exceed federal CWA guidelines. These standards define how much of any particular pollutant can be allowed in surface and ground waters.
These standards apply to a wide range of pollutants, including bacteria, chemicals, nutrients, turbidity and mercury.
However, the standard for any particular lake or stream depends on the designated beneficial uses of that water body. Beneficial uses include drinking water, supporting aquatic life, recreation, and agricultural irrigation, along with several others. Waters designated for drinking water or aquatic life often have different standards for pollutants than waters designated for recreation, agriculture or other uses. For more information on Minnesotas standards, visit the Water Quality Standards page at the Minnesota Pollution Control Agencys web site.
Assessing our waters
The MPCA collects water quality data from state, local and federal agencies, as well as citizen monitors, and then uses this and other information to assess waters for compliance with Minnesotas water quality standards.
So far, weve only assessed a small portion of our states waters. However, of those waters assessed, about 40% have been determined to exceed the standards for at least one pollutant.
Adding waters to the 303(d) Impaired Waters List
If a water body fails to meet one or more of its water quality standards, that water body is considered impaired and is added to Minnesotas Impaired Waters List. This list is also referred to as the 303(d) list which is the section of the Clean Water Act that mandates this assessment and clean up process.
Once a water body is listed as impaired for a certain pollutant, the Clean Water Act requires states to create clean up plan. The main tool for completing this is a process called the Total Maximum Daily Load, or TMDL.
Cleaning up impaired waters: The TMDL
- Total Maximum Daily Load (Number):
- The maximum amount of a pollutant that a water body can receive and still meet water quality standards.
- Total Maximum Daily Load (Study):
- A written plan and analysis of an impaired water body established to ensure that the water quality standards will be attained and maintained through assigned pollution reductions.
For each impairment on the 303(d) list, the Clean Water Act requires completion of a TMDL. A TMDL is basically a pollution reduction plan for the impaired water.
The term TMDL actually has two complementary meanings. In numerical form, it represents total amount of a pollutant that a water body can receive and still meet water quality standards.
The TMDL also represents an extensive study of all the sources of a given pollutant contaminating the impaired water, and the amounts by which each of these contributing sources must be reduced in order to meet the standards.
The TMDL eventually results in a comprehensive pollution reduction plan. These plans dont define how the necessary reductions will be made, but instead details how much contributing sources will be reduced in order to meet the standards. TMDLs are made available for public comment before being submitted to the US EPA for final approval.
Once a TMDL is approved, a detailed implementation plan is created to determine how each contributing source of the pollutant will achieve its required reductions. If the impairment is severe, achieving these reductions often includes extensive restoration activity and can require a substantial investment of time and resources.
Impaired waters in Minnesota
The Minnesota Pollution Control Agency recently announced its draft 2008 Impaired Waters List. This list, updated every two years in accordance with section 303(d) the Federal Clean Water Act, indicates surface waters in Minnesota that have failed to meet water quality standards for their designated use.
The Minnesota 2008 draft Impaired Waters List shows 1,496 impairments on 336 different rivers and 500 different lakes. The years list includes the addition of 287 new listings. Of these new listings, 131 are on lakes and 156 are on stream or river segments. The bulk of all impairments are due to high total phosphorus, turbidity (cloudiness) and high levels of mercury in fish tissue samples. (see adjacent chart)
Once waters are listed, the MPCA is responsible for creating the clean up study portion of the TMDL. Once a water body has an approved TMDL, it is removed from the Impaired Waters List.
Minnesotas 2006 list showed 2,250 impairments on 284 rivers and 1,013 lakes. The main reason for the decrease in total numbers in 2008 is the approved Mercury TMDL.
The Clean Water Legacy Act, passed in June 2006, allocates first-year funding to accelerate water monitoring, TMDL development and restoration activities throughout the state.
Find out more
Minnesota Pollution Control Agency Contacts
- For questions regarding the 303(d) list of impaired waters, contact Howard Markus at 651-296-7295 or 800-657-3864.
- For TMDL planning or questions in general about the TMDL program, contact Jeff Risberg at 651-296-7231 or 800-657-3864.
On the Web
- Minnesotas Impaired Waters web site
- List of Minnesotas impaired waters
- Maps of Minnesotas impaired waters
- Minnesotas water quality standards
- MPCAs Impaired Waters fact sheet (56 KB PDF)
- Minnesotas approved TMDLs and implementation plans
More data from the Impaired Waters List
|Total||New in 2008||2006 Total|
|2008 Draft 303(d) List||1,496||287||2,250|
|% Exotic chemicals||33%||65%|
|Pollutant||Total impairments||% of total impairments|
|Mercury in fish tissue||274||19%|
|Fecal coliform bacteria||147||10%|
|PCBs in fish tissue||134||9%|
|Low dissolved oxygen||63||4%|
|PFOS in water or fish||28||2%|
|Mercury in water||23||2%|