The Montana Department of Environmental Quality is requesting public comment on revised water quality goals for Belt Creek, following the completion of a $13 million water treatment plant that has begun removing acid mine drainage from the creek for the first time in more than a century.
DEQ has drafted a revised Missouri-Cascade and Belt total maximum daily load document to account for a new discharge permit tied to the treatment plant. The agency will host a public meeting on July 21, 2026, from 5:30 to 7:30 p.m. at Belt City Hall, 70 Castner St., and is accepting public comment on only the revised portions of the document through August 6, 2026.
Total maximum daily loads, commonly referred to as TMDLs or water quality goals, establish the maximum amount of a pollutant a waterway can receive and still meet water quality standards. The original Missouri-Cascade and Belt TMDL document was approved by the federal Environmental Protection Agency in 2011. The revised document adds new TMDLs including an aluminum TMDL for the lower section of Belt Creek and arsenic, copper and lead TMDLs for Cottonwood Creek. In anticipation of a potential future change to the human health lead criterion, DEQ also included alternate lead TMDLs that would take effect if that standard is updated.
The revisions come after decades of environmental damage caused by acid mine drainage flowing from abandoned coal mines near Belt. On an average day, the mines discharged more than 200,000 gallons of water containing over 800 pounds of iron, aluminum and other dissolved metals into Belt Creek — contamination that turned the creek’s banks a deep rust-orange color for well over a century.
Several coal mines operated in the Belt area in the late 1800s, with the Anaconda Belt Mine peaking in the 1890s before closing in 1924. Groundwater continued flowing through the abandoned shafts for more than 100 years, forming sulfuric acid and carrying heavy metals into the creek, damaging aquatic ecosystems and harming fish populations.
DEQ began operating the new water treatment plant in November 2025. The facility captures water from the abandoned mine adits, adds lime to raise the pH and precipitate metals into solid form, and discharges pH-neutral, treated water into Belt Creek. Since the plant began operating, the creek has run clear rather than the rust color that residents had long accepted as normal.
The plant was constructed under the DEQ Montana Abandoned Mine Lands Program and funded through federal grants from a fee on coal production. Gov. Greg Gianforte joined DEQ officials to celebrate the plant’s completion in November 2025, calling it the product of decades of work by state and community partners.
Revised portions of the TMDL document are indicated in red underline and strikethrough. Public comments may be submitted to DEQ through August 6.