The impact of nonpoint source pollution from mining wastes on water quality, Elko County, Nevada

Samuel Earman, University of Nevada, Las Vegas


A study was performed at a mine site in Elko County, Nevada to determine the effects on water quality resulting from waste rock at the site. Statistically significant (alpha less than or equal to 0.05) increases of several constituents, including sulfate (272 mg/L), calcium (46 mg/L), and magnesium (39 mg/L), were found to occur in the North Fork of the Humboldt River as it flows through the mine site. Geochemical modeling and historical data suggested that waste rock from the mine is primarily responsible for the increase in dissolved solids concentration. Electrical conductivity of the water exhibits seasonal fluctuations, with high values occurring in association with both snowmelt in the spring, and increased precipitation in the fall. Mass loading of dissolved constituents was found to be controlled by river discharge. Many of the deleterious impacts commonly associated with mine wastes, such as acidification and increases in suspended sediment concentrations were not found to be occurring at the site, due to factors such as carbonate buffering of acidity and the presence of sediment control structures at the site.