Other potential WQS projects considered by MPCA

MPCA is interested in the public’s opinion and comments on these WQS projects that did not make it into the MPCA’s Proposed WQS Work Plan for 2021 to 2023.

Revisions to WQS for bioaccumulative toxics - human health

This topic includes consideration of revisions to WQS for three pollutant groups/pollutants that are based on older science and were developed using outdated methods.

  • Dioxins/Furans (Dx/Fx) are a large group of chemicals that have similar toxicity and shared chemical characteristics. Dx/Fx are not manufactured or produced intentionally but are created when other chemicals or products are made, such as incineration of household trash, chlorine bleaching of pulp and paper, or manufacturing or processing of certain types of chemicals, such as pesticides (CDC factsheet on Dx/Fx/PCBs). They can also be produced in relatively lower concentrations from forest fires and other natural sources. They are persistent in the environment and tend to accumulate in food, mainly animal products such as dairy, meat, fish and shellfish, where they are stored in fats.
  • Polychlorinated biphenyls (PCBs) are also a large group of chemicals with similar toxicity and shared chemical characteristics. Unlike Dx/Fx, PCBs were intentionally manufactured until 1979 and used as insulator fluids in heat-exchangers and transformers, as hydraulic fluids, and as additives to paints, oils and caulks. PCBs are also persistent in the environment and accumulate in food. Some PCBs have similar toxicological effects as Dx/Fx and are important for studying, along with Dx/Fx in fish monitoring programs.
  • Mercury is a well-known environmental pollutant that in some forms can be transmitted in air around the world; see PDF icon 2019 State of the knowledge on mercury (wq-iw4-02h3). It is a metal that occurs naturally in deposits in the earth and can be released by both human and natural activities. Human-related sources of mercury include combustion of coal, waste materials, chlorine-alkali and metal processing, and unregulated gold mining operations. Though concentrations in ambient air and water tend to be low, mercury readily accumulates in fish to levels of concern for consumers. Fish-eating wildlife also can accumulate mercury to levels that affect their health. Excess mercury, specifically methylmercury, in Minnesota’s fish has resulted in the most impaired surface waters.

Surface water pathogens (Escherichia coli or E. coli) – Recreational and human health

MPCA has reviewed extensive datasets in preparation for updating Minnesota’s existing WQS for E. coli, as urged by the EPA at the time its new 304(a) recreational criteria for surface water pathogens (E. coli) was released in 2012. E. coli is a bacterium that is present in human digestive tracts and is used as an indicator of the presence of potentially harmful bacteria, viruses, and other microbiological pathogens in lakes and rivers. For a number of reasons, MPCA decided not to complete this Class 2 revision of the existing standard. They include limited staff capacity and the conclusion that a greater impact will be achieved through WQS revisions that result in improved protection of drinking water sources, as are now being considered as part of the Use Class 1 project (see Proposed water quality standards work plan for 2021 to 2023).

Surface water pathogens are a concern and likely to become more so in the future due to climate change.

Addition of WQS for the pesticides clothianidin and imidiproclid

The Minnesota Department of Agriculture (MDA) recently named clothianidin and imidiproclid as pesticides of concern in surface water. This designation means these pesticides were detected at concentrations of concern to aquatic life in rivers and streams relative to a water quality reference value. Minnesota does not have WQS for these pesticides.

Review and update designated Outstanding Resource Value Waters (ORVWs) (Minn. R. 7050.0335)

ORVWs are exceptional waters designated in Minnesota rules as outstanding, very sensitive, or unique resources that must be maintained and protected to provide future generations with the opportunity to enjoy them. ORVWs are either specifically designated in rule or are unlisted (Minn. R. 7050.0335, subparts 2 and 4). ORVWs were first designated in 1984 and the list has not been updated since 1998. MPCA is interested in the public’s comments regarding the need for updates and revisions to Minn. R. 7050.0335.