The upper reaches of the North Fork of the Gunnison River have been an area of active coal mining for many years. Recently, concerns about impacts of coal mining on surface-water quality have been raised. To answer these concerns, information on existing, or background, water quality must be known. To obtain this information for the study area, a program for the synoptic collection of water quality data was established in 1982. Water quality data were collected on continuously flowing streams in the upper North Fork of the Gunnison River basin in 1982 and 1983. Each site was sampled repetitively as changes occurred in streamflow and specific conductance. (USGS)