EPA approves changes to state water quality standards

Every three years, all states review and (if necessary) revise their water quality standards as a part of the federal Clean Water Act. This year, Minnesota revised its standards.

The changes, initially proposed by the Minnesota Pollution Control Agency (MPCA), include new water quality standards for lakes; extension of the 1 mg/L phosphorus effluent limit to new or expanding discharges above a certain size; and new fish tissue standards for mercury. Also, the state has added new standards for acetochlor and metolachlor, two commonly used herbicides.

The new water quality standards for lakes focus on nutrient loading standards. Previously, Minnesota did not have numeric standards to protect lakes from the negative effects of excess nutrient loading. The adoption of these new standards for lakes will help protect recreational and aesthetic values while ensuring healthy aquatic communities.

The new mercury standards will help protect lakes and rivers along with human health. Currently, more than 1300 lakes and river segments in Minnesota exceed mercury standards. This is especially problematic for Minnesotans because we consume a high amount of locally caught fish — the primary source of mercury exposure for people in Minnesota. As a result, the MPCA is augmenting the current standard that defines a safe level in water with a standard that defines a safe level in fish tissue.

New limits on phosphorus discharges, along with new herbicide standards, will also help improve Minnesota water quality and quality of life.

To learn more, please visit the Proposed Water Quality Standards Rule Revisions page at Minnesota Pollution Control Agencys web site.