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Working to protect the Mississippi River and its watershed in the Twin Cities area
In response to concerns regarding the health and safety of our nation’s 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.
(Summarized in plain English)
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, it’s considered polluted, and a US EPA-approved clean-up plan must be created.
Minnesota adopted its first statewide water quality standards in 1967, and today’s 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 Minnesota’s standards, visit the Water Quality Standards page at the Minnesota Pollution Control Agency’s web site.
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 Minnesota’s water quality standards.
So far, we’ve only assessed a small portion of our state’s waters. However, of those waters assessed, about 40% have been determined to exceed the standards for at least one pollutant.
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 Minnesota’s 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.
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 don’t 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.
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 year’s 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.
Minnesota’s 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.
|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%|