Data on ground-water quality, Carson Valley and Topaz Lake areas, Douglas County, Nevada, for year ending September 1986

Douglas County, Nevada encompasses 708 sq mi and has been one of the fastest growing counties in the Nation, according to the 1980 census. This rapid population growth has led to concern about the present and future impacts of development upon the groundwater. A network of 33 wells was recently established (1985) in the Carson Valley and Topaz Lake areas of Douglas County to characterize the current groundwater quality and its seasonal variability and to monitor temporal responses to changing land-use activities. This report presents data collected from that network during November 1985 through September 1986. The primary drinking water standard was exceeded for fluoride at two domestic wells, for nitrate-nitrogen at one domestic well, and for arsenic in one non-domestic shallow monitoring well. Secondary drinking water standards were exceeded as follows: pH at one public-supply well and one domestic well; sulfate at one shallow monitoring well; and manganese at three shallow monitoring wells and one public-supply well. Concentrations of unidentified organic compounds were estimated by gas chromatograph and flame ionization detector for groundwater samples collected from 30 network wells. Seven wells (2 domestic and 5 non-domestic) had concentrations greater than 10 micrograms/L relative to the internal standard compound perdeuteronaphthalene. (Thacker-USGS)