State of Montana Asks EPA to Recognize Thompson Falls Clean Air Status

• Moira Davin
• December 01 2021

HELENA – The Montana Department of Environmental Quality (DEQ) has made a formal request to the Environmental Protection Agency (EPA) to redesignate the Thompson Falls area as meeting national air quality standards.

The redesignation from nonattainment to attainment means the Thompson Falls area is in compliance with the National Ambient Air Quality Standards (NAAQS) for particulate matter with a diameter less than or equal to 10 micrometers (PM-10).

“This redesignation means healthier air for the people in the Thompson Falls area,” said Bo Wilkins, bureau chief of DEQ’s Air Quality Program. “The City of Thompson Falls and Sanders County have been our partners in this effort, and we commend them for the steps they have taken to meet air quality standards.”

The Thompson Falls area was designated as nonattainment by the EPA for the PM-10 standard in 1993. Since then, the area has implemented measures to attain the air quality standard.

The most significant source of PM-10 in the area was dust generated from paved and unpaved roads. Sanders County and the City of Thompson Falls adopted a plan that required paving, specified the type of material that may be used for sanding and chip sealing, and prioritized street sweeping.

The process for demonstrating that an area should be redesignated requires extensive data gathering and analysis. DEQ worked with Sanders County, the City of Thompson Falls and the EPA to demonstrate that Thompson Falls now meets the criteria for redesignation. The request has been signed by Governor Gianforte and submitted to the EPA for review. The area will remain under an EPA approved maintenance plan for the next 20 years to ensure protection of air quality.