By Mike Shea

This concerns Rise Grass Valley‘s (Rise GV) application with Nevada County for a permit to reopen the Idaho-Maryland gold mine. If your house is on a well and you live in the Cedar Ridge area or in the vicinity of Brunswick, Greenhorn, Loma Rica, Town Talk, and Idaho-Maryland roads, reopening the mine may impact your well.

Before the mine can be worked, the water flooding the mine will have to be pumped out. The Groundwater Hydrology and Water Quality Analysis Report for the Idaho-Maryland Mine Project is inconsistent about how much water they will remove. In one place it says they will pump out 815 million gallons; ¹⁾Groundwater Hydrology and Water Quality Analysis Report for the Idaho-Maryland Mine Project, March 2020 p.4. Also, Idaho Maryland Water Treatment Plant Design Report, November 2019, Table 2-1. in another, it says they will remove about 576 million gallons.²⁾Groundwater Hydrology and Water Quality Analysis Report for the Idaho-Maryland Mine Project, March 2020, p.70. Either way, that’s a lot of water.

Once the mine has been dewatered, natural groundwater would continue to flow into the underground workings. That water also would have to be pumped out at a rate Rise GV estimates to be approximately 1,224,000 gallons a day!³⁾Ibid. That may be the same groundwater your well depends on.

The Groundwater Hydrology report says of the estimated drawdown (decrease) of water in local wells, “Within the East Bennett area, the maximum additional drawdown due to the proposed project would be in the range of five to 10 feet.”⁴⁾Ibid, p.116. In response, Rise GV says it will install a NID pipeline along a 1¼-mile section of East Bennett Road and will pay to have houses along East Bennet Road hooked up to NID if the homeowner wishes. But homeowners who previously had free well water will have to pay the monthly NID water bill.

The mine’s underground mineral rights extend far beyond East Bennet Road. The hydrology study assures well owners in other areas that the “maximum potential additional drawdown in the perimeter areas is less than 10 percent of the available water column in individual wells.”⁵⁾ Ibid, p.117. It further suggests that “In other areas around the perimeter of the mine workings and in areas where expansion could occur, the projected maximum drawdown in private wells is less than two feet.”⁶⁾ Ibid. Apparently, Rise GV doesn’t see this as a concern, so has made no provisions to provide NID hookups to well owners in other locations whose wells may go dry from the dewatering or the pumping of groundwater.

Even though the hydrology study says that “the project would not have any significant impact on groundwater supplies”⁷⁾Ibid. it also says “99 percent of groundwater inflow will occur within 550 feet of the ground surface.”⁸⁾Ibid, p.75 One has to wonder how sucking out over a million gallons of groundwater a day from the top 550 feet of soil could affect our forests. Will it further dry out our trees and increase the fire danger in our community, which is already rated as a “Very High” Fire Hazard Severity zone?

The mine’s mineral rights boundaries can be found in Figure 3A of the Idaho-Maryland Mine Project Description at

https://www.mynevadacounty.com/2882/Application-Documents—Rise Grass-Valle

Rise GV is currently seeking investors and is painting a rosy picture of their chances of getting the mine approved. I encourage you to make your voice heard now, before it is too late.