FAQ: Idaho-Maryland Mine

By Community Environmental Advocates Foundation


Idaho-Maryland Mine Frequently-Asked Questions


What is the mine reopening proposal?

Rise Gold, a junior mining company with questionable experience, submitted an application to restart mining operations at the old Idaho-Maryland Mine in Grass Valley. Initially, the mine will be dewatered and some operational structure will be built on the surface. Then, underground development will begin. The permit application describes a drill and blast regime to remove 1,500 tons of rock per day, operating 24 hours a day, 7 days a week for the 80-year life of the project. The main processing facilities will be on the corner of Brunswick Rd and E. Bennett. Mine operations would create approximately 2.4 million cubic yards of mining tailings and rock waste deposited at two locations. An additional site will be located closer to downtown Grass Valley at the old Idaho-Maryland Mine location along Idaho Maryland Rd.


What are the potential impacts of the mine?

Even using the most current mining technologies and techniques, gold mining is an inherently high-risk venture with potentially negative impacts. Chief among them are concerns about water quality and quantity due to mine dewatering, significantly higher levels of noise and vibration impacting local residents, truck traffic, and increased levels of dust and industrial emissions that impact air quality locally and contribute to greenhouse gases. The prospect of replacing open forested areas with two huge mining waste piles threatens local wildlife and quality of life for neighbors. Neighbors also may have impacts to wells and lowered property values.


Read more about the top 8 reasons to stop the Idaho-Maryland Mine.


Where is the mine? Do the mineral rights extend beyond the borders of the site?

The mine would be located at two sites; the Brunswick Industrial Site is 119 acres, at the junction of East Bennett Street and Brunswick Road and along Brunswick Rd. This is where the ore processing facilities and mine access shafts are planned. The second, 56-acre Centennial site, which was the site of the old Idaho-Maryland Mine and processing facilities, is along Idaho-Maryland Rd, east of Centennial Drive.


Map of mining site locations


As shown in the map below, the underground mineral rights cover a huge area, about 2585 acres. These mineral rights extend west under Highway 49 and completely under Sierra Nevada Memorial Hospital, east of Brunswick Road under the Nevada County Airpark, north as far as Plaza Drive in Glenbrook Basin, and to Highway 174 and much of Cedar Ridge. The subterranean mining operations can potentially include all of this area and to within 200 feet of the surface.


Map showing mining site boundaries (red) and mineral rights boundaries (orange)


Who is the lead agency in the government?

Nevada County Planning Department is the lead agency preparing the EIR (Environmental Impact Report) pursuant to CEQA (California Environmental Quality Act) guidelines. Raney Planning & Management, Inc. is the consulting firm selected by Nevada County Supervisors to provide expert analysis and draft the EIR. Multiple Nevada County and City of Grass Valley departments will review the work in progress and draft EIR submittals including Planning, Engineering, Transportation, Environmental Health, Fire Departments, and County Sheriff, and outside agencies such as Fish and Wildlife.


How does the decision process work?

Once Nevada County Planning determines an EIR (Environment Impact Report) is required, they need to prepare a scope of work based on the applicant’s (Rise Gold’s) project description and submittals. A consulting firm is selected to complete the EIR. County Planning prepares a NOP (Notice of Preparation) to inform the community about the project. Included in the NOP is information about the location, project description, an issues list and brief description of each, and details about the project’s operational profile. The NOP gives the community a minimum of 30 days to review the project and identify issues and concerns that need to be addressed by the consultant during the EIR process and in the final document.


These comments are reviewed by the lead agency and handed off to the consultant. The ADEIR (Administrative Draft EIR) is prepared for review by the lead agency (review is typically 90 days), their comments and requests lead to a Draft EIR. The DEIR is published and is made available for public comments for at least 45 days. Public hearings are generally held by the Planning Commission at this stage. All of the comments from the public have to be addressed and all the questions answered. Changes based on comments may then be made to the DEIR by the consultant to produce the Final EIR. The Final DEIR again undergoes County Departments review, Planning Department review, and Planning Commission Hearings, and Board of Supervisor Hearings. The Board of Supervisors ultimately vote on whether to approve the project.


How will the mine impact our local creeks and rivers?

At the Brunswick site, the first sixth months of mining operations would include “dewatering” the abandoned mine shafts by pumping 3.6 million gallons of water daily into South Fork Wolf Creek. Once the mine is dewatered, 1.2 to 3.6 million gallons per day (1.9 to 5.6 cfs) will be pumped from the underground workings to maintain the dewatered state.


Before discharging into the creek, the water would need to be treated to remove the metal contaminants. This water treatment facility will have to operate in perpetuity to prevent the discharge of contaminated water, even after the mine closes in 80 years. These high, artificial water discharges into the creek will disrupt the natural flow regime in the creek, disturbing the life cycles of the organisms that sustain the ecology of this riparian corridor.


It should be noted that it is not possible to predict the full effect that dewatering will have on the underground hydrology in the vicinity with absolute certainty. This includes nearby wells, the creek, riparian zones, and subterranean groundwater.