![[logo] US EPA](http://www.epa.gov/epafiles/images/logo_epaseal.gif){kind=logo}
Great Lakes Initiative
Final Regulation to Ban Mixing Zones in the Great Lakes
Fact Sheet; EPA 821-F-00-012
EPA is taking final action to ban the use of mixing zones that dilute toxic chemicals discharged into the Great Lakes system. This action prohibits new discharges of toxic chemicals into mixing zones and phases out the use of existing mixing zones in the Great Lakes over the next ten years. It has been found that toxic discharges into mixing zones build up in the Great Lakes system and threaten human health, aquatic life and wildlife. This regulation will ban up to 700,000 toxic pounds annually of chemicals that are discharged into the lakes and that accumulate in fish and wildlife, including mercury, dioxin, PCBs and pesticides. Mercury discharges alone will be reduced by up to 90 percent.
Background
A mixing zone is an area where pollutants are mixed with cleaner receiving waters to dilute their concentration in the water. Inside a mixing zone, discharges of toxic pollutants are allowed to exceed the water quality limits set by a state. Outside or near the boundary of the mixing zone, levels of pollutants must meet the water quality standards set for that particular body of water. Despite their great depth and size, the Great Lakes are particularly vulnerable to the buildup of toxic pollutants. Although the waters inside a mixing zone dilute the concentration of a pollutant, certain pollutants may build up in fish, plants and wildlife in the water. Toxic pollutants that bioaccumulate in plants, fish and other wildlife as they move through the food chain are referred to as bioaccumulative chemicals of concern. These include mercury, polychlorinated biphenyls (PCBs), dioxin, chlordane, DDT, and mirex, as well as 16 other highly bioaccumulative chemicals.
Chemicals that bioaccumulate in the food chain are of great concern because long-term exposure to them can increase the risk of cancer, birth defects, genetic mutations, and reproductive impacts. Toxic impacts include abnormalities in the liver and endocrine systems. People may be exposed to these bioaccumulative chemicals of concerns by eating fish caught in the Great Lakes. Although the Great Lakes states issue fish consumption advisories to protect people who eat fish caught in the Great Lakes, the banning of mixing zones also will protect human health by reducing bioaccumulative chemicals dumped into the Great Lakes and improving water quality.
History of Mixing Zone Ban
In l995, EPA and the Great Lakes states agreed to a comprehensive plan to restore the health of the Great Lakes. The Final Water Quality Guidance for the Great Lakes System, also known as the Great Lakes Initiative, includes criteria for states to use when setting water quality standards for 29 pollutants, including bioaccumulative chemicals of concern and prohibited the use of mixing zones for these toxic chemicals. The entire plan, including the mixing zone prohibition for the bioaccumulative chemicals, was challenged in federal court.
In June l997, the U.S. Court of Appeals in the District of Columbia upheld the majority of the provisions in the Great Lakes Water Quality Guidance, but vacated the mixing zone prohibition and remanded the provision to EPA for further consideration. On September 24, 1999, Administrator Browner announced EPA's proposal to reinstate the mixing zone provision. This decision was based on continuing evidence that the highly bioaccumulative nature of these toxic chemicals presents a significant potential risk to human health, aquatic life and wildlife. After reconsideration of the factual record, EPA is reinstating the provision to prohibit mixing zones for bioaccumulative chemicals of concern in the Great Lakes.
The final rule
EPA is issuing a final rule to prohibit mixing zones for bioaccumulative chemicals of concern in the Great Lakes Basin, which includes areas of the eight Great Lakes states: New York, Pennsylvania, Ohio, Minnesota, Indiana, Illinois, Wisconsin, and Michigan. Five of these states Illinois, Indiana, Michigan, Minnesota, and Wisconsin already prohibit mixing zones for bioaccumulative chemicals of concern in the Great Lakes Basin. The other three states New York, Ohio, and Pennsylvania will have 18 months to adopt similar provisions prohibiting mixing zones for these toxic chemicals.
This rule bans new discharges of bioaccumulative chemicals into mixing zones and phases out the use of existing mixing zones over a ten year period. EPA includes a limited exception that would allow minimal use of mixing zones for discharges of bioaccumulative chemicals for existing facilities that may suffer unreasonable economic effects.
This rule applies to all industrial and municipal facilities with Clean Water Act permits that discharge bioaccumulative chemicals into the Great Lakes system. EPA estimates that about half of the 600 major dischargers currently discharge into mixing zones will be affected by this final rule.