ST. PAUL — The Minnesota Pollution Control Agency (MPCA) has proposed site-specific water quality standards for salinity in the Rock River, downstream from the city of Luverne’s wastewater treatment plant. If adopted, the new standards would more accurately reflect what is needed to ensure the water can be used for cropland irrigation.

Minnesota rule allows site-specific standards to be developed when local circumstances support a modification to statewide standards. The standards would apply to about 16 miles of the Rock River from Luverne to the Iowa border. The city is completing a $14 million wastewater treatment upgrade to significantly improve the quality of the water it discharges.

As a Class 4A water, the Rock River must be able to support crop production without damage or adverse effects. The proposed standard addresses two parameters in the water: specific conductance and sodium. The Class 4A sodium value will be replaced with a numeric standard for sodium adsorption ratio (SAR). According to current research, protecting soil health from excess SAR also protects from direct sodium toxicity to plants. The change may also contribute to Luverne’s capacity for industrial development.

To learn more about the proposed standard, visit pca.state.mn.us/public-notices. The agency will host an informational meeting about the proposed standard via Webex at 5 p.m. June 11. For access details, visit pca.state.mn.us/water/site-specific-water-quality-standards.

The MPCA is accepting written comments on the proposed standard until 4:30 p.m. June 18. Send written comments to or request information from Scott Kyser (651) 757-2665, Minnesota Pollution Control Agency, 520 Lafayette Rd. N., St. Paul 55155. Comments must state your interest in the site-specific standards, the action you wish the MPCA to take including specific references, and specific reasons supporting your position.