Removal of drinking water, industrial, and irrigation uses for the trout stream portion of the Dark River

Dark River in St. Louis CountyProposed amendments to Minnesota water quality standards. (Revisor's ID: R-04572)

The MPCA has received a petition to remove three designated uses for the trout stream portion of the Dark River in St. Louis County: drinking water (Class 1B), industrial consumption (Class 3), and agricultural irrigation (Class 4A). The MPCA has reviewed the petition and is considering removing the uses based on the fact that the uses do not currently exist and are also not reasonably expected to be attainable uses in the future.


Minnesota’s surface waters are currently assigned multiple beneficial uses (e.g., drinking water, aquatic life, industrial consumption) based on which beneficial uses are or should be attained in those waters. Different physical and chemical standards apply depending on the beneficial uses that need to be protected in each water. Unless specifically reclassified in rule, all waters are by default assigned the uses for aquatic life, industrial and agricultural use, wildlife, and aesthetic enjoyment. Minn R. 7050.0405 establishes that any person may petition the MPCA to consider the reclassification of a water body by submitting evidence that:

  1. a beneficial use does not exist; or
  2. a beneficial use is not attainable.

U.S. Steel Corporation submitted a petition on August 31, 2018, requesting specific changes to the use classification of the portion of Dark River currently classified as a trout stream. This portion of the Dark River (AUID 09030005-525) originates 1.59 miles downstream of Dark Lake and continues for 7.91 miles. The portions of the Dark River upstream and downstream of this section are not currently being considered for reclassification.

The petition specifically requests to remove the Class 1B (drinking water), Class 3 (industrial consumption) and Class 4A (agricultural irrigation) beneficial use designations from the trout stream portion of the Dark River on the basis that they are not existing or attainable uses. U.S. Steel provided the documentation required under Minn. R. 7050.0405 in their petition, and the MPCA thoroughly reviewed the petition request and agreed that the information submitted supports the requested review of the designated uses.

However, additional water quality data submitted by U.S. Steel to MPCA in a second use-removal request indicated that there has been a measured exceedance of the Class 4A water quality standard for specific conductance downstream of the trout reach. Minnesota Rule (7050.0155) and federal regulations (40 CFR § 131.10(b)) require MPCA to protect for downstream water quality standards. Specific conductance concentrations of upstream waters, especially if Class 4A water quality standards are removed, do not provide for attainment of water quality standards in waters downstream of the trout reach. Therefore, MPCA is unable to remove the Class 4A designated use for the trout reach. For the Class 1 and Class 3 designated uses, the MPCA is continuing to review the effect of Minnesota statutes that prevent permanent appropriations from trout streams (for uses such as drinking water, industrial, or irrigation) on the use and value of the waterbody covered in this petition and implications for the use of trout reaches statewide.

All other use classes, and the standards that protect those uses, including the protection of aquatic life and the identification of this water as a trout water, will not be affected by the use classification changes being considered.

Schedule and opportunities to participate

Task Schedule
Publish request for comments March 18, 2019
Informal stakeholder engagement TBD
Public notice of hearing/public comment period TBD
Final adoption of rules TBD

TBD: To be determined

Rulemaking references

Request for comments

PDF icon Comments in response to Request for Comments for Dark River (wq-rule4-23d)

Technical support documents

PDF icon U.S. Steel petition to remove designated uses on Dark River Trout Reach (wq-rule4-23a)

PDF icon MPCA response (wq-rule4-23f)

Existing rules and statutes

Minnesota Rules chapter 7050 establishes designated uses for rivers, streams, and lakes. The proposed amendments affect designations of a listed water, which are incorporated by reference in Minn. R. 7050.0470.

MPCA staff contacts

Technical questions about use classifications and proposed changes: Catherine Neuschler,

Questions about the rulemaking and submitting comments: Anna Hotz,