The Montana Department of Environmental Quality issued its Record of Decision Thursday for a proposed copper mine in Meagher County.
The Black Butte Copper Project would be located about 15 miles north of White Sulphur Springs and would be operated by Tintina Inc.
Approval of the project comes a little more than a year after state officials released the project's Environmental Impact Statement, or EIS.
According to the EIS, the mine would impact just over 300 acres of land with little to no direct impact on hunting, fishing or other recreation opportunities in the area.
Some anglers, guides and conservationists had expressed concerns over the mine's proximity to the Smith River, one of Montana's premiere fishing destinations.
The EIS reported the project could substantially lower groundwater levels around the mine reducing some flows in nearby creeks but would have little impact on surface water levels and water quality.
According to DEQ, it is requiring several stringent measures to ensure water quality around the project.
- Early in the review process, DEQ identified a potential flow reduction in Coon Creek due to groundwater being diverted for mining activity. To ensure compliance with the Montana Water Quality Act, Tintina must mitigate this potential impact by augmenting flows in Coon Creek. Tintina applied to the Department of Natural Resources and Conservation to acquire the water right permits and water right changes necessary for this mitigation. While limited pre-mining activities will be allowed, DEQ will not allow Tintina to begin any activities that have the potential to impact flows in Coon Creek until the required water rights are in place.
- DEQ is requiring, and Tintina has agreed to, protective measures to ensure water quality is not degraded. The mine will not be allowed to discharge any water involved in ore processing, only storm water and ground water that has been treated before discharge. No water may be discharged directly to surface water. Instead, the discharge must be injected into the ground where additional mitigation will take place before it reaches surface water, and Tintina must still meet the more stringent surface water quality standards.
- Tintina originally applied to have a mixing zone, which is where the discharge is mixed with water for dilution, and DEQ denied that request, requiring unprecedented levels of protection. As a result, the mine will need to treat water using advanced technology, including double reverse osmosis typically used for treating drinking water, to meet the very stringent water quality standards.
- The mine will also actively monitor water quality at several locations to ensure standards are being met, and will adjust water temperature in real time so there is no harm to trout and other aquatic life caused by temperature changes.
- Tintina will not be allowed to discharge any water at all during the months of July through September, when nitrogen in the water may stimulate algae growth.
- DEQ, in partnership with Montana Fish, Wildlife & Parks, is in its third year of a comprehensive baseline algae study on the Smith River to determine possible causes. If the results of the study suggest additional precautions may be necessary, DEQ can require Tintina’s permit to be updated to address possible impacts.
Tintina could bring in as many as 200 contractors during construction and 235 employees once the mine is operational.
The company would construct, operate and reclaim the project site over 19 years.