Amendments to Water Quality Standards: Use classifications 3 and 4

The Clean Water Act requires a regular review of state water quality standards, and one important aspect of that review is the updating of designated use classifications. In this rulemaking, the MPCA proposes to amend the existing rules governing water quality standards for industrial consumption (Class 3) and agricultural and wildlife usage (Class 4). Please note that this rulemaking will not address the Class 4A wild rice sulfate standard, which is the subject of a separate rulemaking effort.

In summary, the changes being considered would:

• replace numeric standards for existing subclasses 3A–3D with a single narrative standard, condensing the subclasses into a single industrial consumption use class;
• replace numeric Class 4A standards for bicarbonate, boron, pH, specific conductance, total dissolved salts and sodium with a narrative standard and include a process to translate the narrative standard into a numeric effluent limit or limits for permitted dischargers;
• update numeric standards for Class 4B to reflect current science;
• remove the Class 4C designated use (protection of wetlands for agriculture and wildlife) and designate wetlands as Classes 4A and 4B instead of 4C;
• move wetland standards for chloride and settleable solids from Classes 3D and 4C to Class 2D, and move the narrative Class 4C standard to 7050.0186, to more appropriately reflect the uses being protected; and
• maintain applicability of Class 3, 4A, and 4B uses on all waters of the state.

Learn more: Making changes to Class 3 and 4 standards will protect state waters while lowering regulatory hurdles (wq-rule4-17e)

Rulemaking and technical support documents

2019 Request for comments

• Request for comments: 2019 (wq-rule4-17c)
• Technical support document (wq-rule4-17d)
• Comments Received in 2019 RFC period (wq-rule4-17f)

2016 Request for comments

• Request for comments (wq-rule4-17a)
• Comments received in response to RFC open 2/8/16 to 4/8/16 (wq-rule4-17b)

2010 Evaluation from the University of Minnesota’s Department of Bioproducts and Biosystems Engineering.

• University of Minnesota Class 3 and Class 4 Water Quality Standards Review

Draft rule language

Not yet available.

You can register at GovDelivery to be notified when draft rule language is published.

Schedule/public participation opportunities

Register at GovDelivery to receive notice of upcoming Use Class 3 and 4 rulemaking activities.

Contact information

For questions about the status of the rulemaking or how to submit comments:
Katie Izzo: katie.izzo@state.mn.us, 651-757-2595

For technical questions about these use classifications and the proposed changes:
Scott Kyser: scott.kyser@state.mn.us, 651-757-2665