DEQ Press Releases

Driscoll, Paul

DEQ Accepting Public Comment on Draft Wastewater Discharge Permits for Stillwater Mining

Helena – The Montana Department of Environmental Quality is accepting public comments on draft Montana Pollutant Discharge Elimination System (MPDES) permits for the Stillwater Mining Company’s Stillwater and East Boulder Mines.

The first updates the existing permit for the East Boulder Mine located near Big Timber. The update authorizes discharge of treated adit water, which is ground water that has infiltrated the underground mine workings, either directly to the East Boulder River or to ground water associated with the East Boulder River. It also authorizes treated sanitary sewer discharge from the domestic septic drainfield.

The draft permit includes technology-based and water quality-based effluent limits to prevent degradation of the East Boulder River. Monitoring, Best Management Practices, and a wastewater optimization study are also required in the draft permit.

The second draft permit updates the existing permit for the Stillwater Mine located near Nye. The permit covers the discharge of mine drainage water to the Stillwater River from the Stillwater Mine. The water is treated to remove total suspended solids and reduce nitrogen concentrations. The permit includes one as yet unconstructed outfall for discharge directly to the Stillwater River and two discharges to ground water and the Stillwater River via percolation ponds.

These new limits include technology-based effluent limits for pH and total suspended solids, and water quality-based limits for aluminum, cadmium, copper, iron, lead, mercury, nickel, silver, zinc, nitrate plus nitrate, and ammonia.

DEQ has prepared the draft wastewater discharge permits, fact sheets, environmental assessments and the department’s tentative determinations. The documents are available on the DEQ website at and at the DEQ Metcalf Building in Helena. 

The deadline for submitting comment is September 2, 2015. DEQ will accept requests for a public hearing during the public comment period.  A request must be in writing and state the nature of the issue to be raised.

Comments should be sent to: DEQ Permitting and Compliance Division, Water Protection Bureau, PO Box 200901, Helena, MT  59620 or by email to: 

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