Water quality of streams and lakes in the Guanella Pass area could be affected by the proposed reconstruction of the existing road through the area. During water year 1995 (October 1, 1994, to September 30, 1995), data were collected that provide reconnaissance information about thehydrology, water quality, sediment transport, biology, and bulk atmospheric-deposition in the Guanella Pass study area. Data were collected at 5 stream monitoring stations, 23 synoptic-stream sites, 11 road-runoff sites, 8 ground-water sites, 4 lake/reservoir sites, 2 snow-precipitation sites, 11 biological sampling sites, and 12 bulk atmospheric- deposition sites.