In Minnesota, the vast majority of impaired water bodies reported to EPA by the Minnesota Pollution Control Agency (MPCA) are based on mercury impairments. The State water quality criterion for mercury, which is the basis for determining if a water body is impaired, is the mercury concentration in representative fish from the water body. This criterion is in contrast to most water quality criteria, which are based on concentrations in water.
To address mercury impaired waters statewide, MPCA will be controlling air emissions of mercury. The MPCA Statewide Mercury TMDL established a need for a 93% reduction in State emissions compared to a 1990 baseline.
Because current air emissions of mercury need to be reduced, the issue of permitting new sources or expanding existing sources of mercury becomes a critical issue. On February 25, 2009, MPCA released a working draft of its proposed guidelines for issuing air permits for new or expanded sources, under the constraints of the the Mercury TMDL.
The proposed guidelines for any existing mercury-emitting facility with an MPCA air permit planning to expand and any new facility expected to emit mercury would require implementation of the measures listed below to address the increases. An expanding source that demonstrates no net increase from their proposed project would not be subject to these requirements.
“1. Employ the best mercury control available. The MPCA expects facilities to explore all pollution prevention opportunities and utilize the best control technically feasible considering environmental, energy and economic impacts. If best controls reduce emissions by less than 90%, the new source will be subject to periodic review for opportunities for improved control efficiency;
2. Complete environmental review as applicable, including evaluation of local and cumulative impacts per MPCA guidelines;
3. During permitting, the facility will provide an assessment of whether its added emissions will impede progress toward attaining the sector's pound/year air emission goal The MPCA may periodically request that this assessment be updated as the sector's goal approaches.
4. For new or expanding facilities emitting more than 3 pounds per year (after applying best controls) the facility will demonstrate equivalent reductions from existing sources. The facility will demonstrate that the reductions will be ongoing and will exceed reductions already included in stakeholder recommendations or called for by any other policy or requirement. Equivalent reductions can also be created by reducing emissions ahead of schedule.
5. If equivalent mercury reductions from another facility in Minnesota can not be identified, a new facility emitting between 3 pounds and 9 pounds per year may propose alternative mitigation strategies in lieu of an equivalent in-state air emission reduction. Alternative mitigation strategies will demonstrate an environmental benefit related to mercury and will be consistent with the objectives of the TMDL.
6. During permitting, submit a plan to the MPCA describing the facility's specific plan for reductions described in 1 - 5 above. "
MPCA will issue permits with enforceable conditions for new or expanded sources based on the facility's Mercury Reduction Plan. MPCA plans to strictly enforce sector targets. Increases in a sector's emissions will not be allowed to impact the sector's ability to reach its interim and final annual air emission goals.
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