During the Environmental Impact Report (EIR) for Rise Gold Corp's application to reopen the Idaho-Maryland Mine, water quality samples were published which indicated that the water leaving lower drainage tunnels from the underground works were well above threshold levels for several heavy metals.

The mine drains the polluted water from the flooded Idaho-Maryland Mine directly into the main branch of Wolf Creek at several points near Centennial Drive. The contamination is well documented. For example, test results in a document provided for Rise’s own environmental studies, “Groundwater Hydrology and Water Quality Analysis Report for the Idaho-Maryland,” EMKO, February 2021, show that the mine effluent contains arsenic, ammonia, and other contaminants exceeding safe thresholds. An April 2019 Environmental Protection Agency (EPA) Site Inspection Report shows mine drain outflows have high levels of Arsenic, Barium, Chromium, Cobalt, Copper, Lead, Manganese, Nickel, and Zinc.