This report provides a general assessment of effects that the current and potential mining activities during the next 5 years may have on the water resources in each of the 34 hydrographic areas in the Humboldt River Basin of northern Nevada. Nearly 40 active gold mines are operating in the basin; of these, 15 are large-scale, open-pit mines. The potential effects of mining were assessed for seven water-resource characteristics or features at various distances from the mining operations. These characteristics are ground-water levels, springs, perennial streams, shallow ground-water areas, sediment transport, agricultural irrigation, and fish and wildlife habitat. The characteristics and features were evaluated at two distances; local (within 2 miles of the operation) and areal (from 2 to 6 miles away from the operation). Additionally, ground-water levels were evaluated at the regional distances: local (with 2 miles of the operation) and areal (from 2 to 6 miles away from the operation). Additionally, ground-water levels were levels were evaluated at the regional distance (more than 6 miles away from the operation). A numerical ranking scale, ranging from a large change expected to no change expected, was developed for each characteristic and feature. For each hydrographic area in the basin, a single value was assigned for each characteristic at each distance. This value represents the greatest change expected to occur in that hydrographic area. The study results show that the greatest changes are expected in two hydro- graphic areas: Pumpernickel Valley and Kelly Creek Area.