On September 22, 2014, the Minnesota Pollution Control Agency (MPCA) published notice in the Minnesota State Register (39 SR 386),of final amendments to its air quality rules related to mercury air emissions reduction and reporting. The new rules, which became effective September 29, 2014, partially implement Minnesota’s 2007 Mercury Total Maximum Daily Load (TMDL) study.

Mercury air emissions are the primary cause of elevated levels of mercury in Minnesota lakes and river. Minnesota’s mercury TMDL sets a target for fish tissue concentration of mercury that is generally safe for human consumption. (Source: www.epa.gov -- Fish Advisories page.)

Mercury air emissions are the primary cause of elevated levels of mercury in Minnesota lakes and river. Minnesota’s mercury TMDL sets a target for fish tissue concentration of mercury that is generally safe for human consumption. (Source: http://www.epa.gov — Fish Consumption Advisories page.)

MPCA adopted the mercury TMDL under the federal Clean Water Act to address elevated mercury levels in two-thirds of Minnesota’s lakes and rivers. Because 99 percent of the mercury that contaminates Minnesota’s surface water is deposited in the water from the air (with the majority of these emissions originating from out-of-state sources), the TMDL indicated that stricter controls upon mercury air emissions were needed to meet federal water standards. The TMDL study established a target of no more than 789 lbs./yr. of mercury air emissions by 2025 for sources in Minnesota. This represents a
76 percent reduction from 2005 levels, a goal that MPCA’s new rule amendments are designed to help achieve.

MPCA’s amendments generally apply to stationary sources (total facility) that have actual mercury air emissions of 3 lbs./yr. or more after controls, a list that includes industrial, commercial and institutional boilers as well as taconite mining operations. Under the rules, qualifying facilities must submit a mercury reduction plan to meet their sector’s specified reduction target per the TMDL Implementation Plan. (For example, the Implementation Plan calls for taconite facilities to reduce their mercury air emissions by 72 percent compared to the greater of 2008 or 2010 levels.) The facilities’ reduction plans must be approved by MPCA and included in a permit or other enforceable document. The facilities must also submit an annual mercury emission inventory to the MPCA. In addition, the rules incorporate by reference certain federal performance standards for mercury control that are already applicable to the affected stationary sources.

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