RE: Response to Citizen Complaints; Cross Gold Mine; DRMS File No. M-1977-410

The Division of Reclamation, Mining and Safety (DRMS) received multiple citizen complaints from November 2021 through January 2022 regarding the Cross Gold Mine, File No. M-1977- 410. While various concerns were expressed in the complaints, the primary concern (under DRMS jurisdiction) was regarding potential impacts the mine discharge may have had on surface water and groundwater resources in the vicinity of the mine, particularly to downstream wells.

Pursuant to Hard Rock Rule 3.1.6, disturbances to the prevailing hydrologic balance of the affected land and of the surrounding area and to the quantity or quality of water in surface and groundwater systems both during and after the mining operation and during reclamation shall be minimized. Additionally, mine operators are required to be in compliance with applicable federal and Colorado water quality laws and regulations, including statewide standards adopted by the Water Quality Control Commission.

The Cross Gold Mine discharges groundwater through the Cross Mine and the Idaho Tunnel portals. The groundwater is treated to meet aquatic life standards before it is discharged into Coon Track Creek. The discharge of treated wastewater is regulated by the Colorado Department of Public Health and

Environment, Water Quality Control Division (WQCD) under CDPS Permit No. CO0032751. In the course of investigating whether or not the discharge of groundwater from the Cross Gold Mine impaired the quality of groundwater in downstream wells, DRMS reviewed the available water quality data associated with the following:

• Domestic well – single sampling event provided with anonymous citizen complaint

• CDPS Permit No. CO0032751 – provided by WQCD

• Coon Track Creek, Middle Boulder Creek, and Barker Reservoir surface water sampling data – provided by the City of Boulder

Upon reviewing the available water quality data for the Cross Gold Mine and the surrounding area, DRMS has found no evidence indicating groundwater discharges from the mine led to degradation of surface and groundwater resources. DRMS reviewed all of the past data from the Cross Gold Mine, including exceedances of discharge standards and found that all discharges were below drinking water standards.

DRMS also considered factors such as the distance from the mine to the nearest domestic wells and the quality of water in Coon Track Creek.

DRMS is committed to ensuring the Cross Gold Mine remains in compliance with all applicable water quality standards and will consider and review any additional water quality data as it becomes available.

[Editor’s note: This email has been submitted by multiple local residents and is being printed with permission of the Colorado Division of Reclamation, Mining and Safety.)