Water-quality data for the 28 sites in the West Virginia ambient ground-water-quality network and for wells in the U.S. Geological Survey National Water Information System (NWIS) data base for West Virginia were analyzed statistically to identify any water-quality trends and relations and to compare data from the two data sets. Data for 10 selected properties and constituents (pH, fecal coliform, iron, manganese, sulfate, hardness, nitrate plus nitrite, chloride, fluoride, and dissolved solids) were grouped by geologic unit, topographic setting, well depth, and season; simple statistical descriptors such as mean, median, maximum, minimum, standard deviation, and 10th and 90th percentiles were computed for each property and constituent and are summarized in tables.

Analysis of the data for wells from the NWIS data base showed that highest median concentrations of dissolved iron and dissolved manganese are in samples from the Lower Pennsylvanian units, which are found mainly in the low-sulfur coal fields of southern West Virginia; the highest median concentration of dissolved sulfate is in samples from the Quaternary alluvium along the Ohio and Kanawha Rivers; and the highest median hardness and concentrations of dissolved nitrate plus nitrite are in samples from the Cambrian and Ordovician karst limestone units found mainly in the Eastern Panhandle. The highest median concentrations of dissolved iron and dissolved manganese are in samples from valley wells and wells of shallow depth, and hardness is greatest in samples from hilltop wells. Analysis of data for all wells and springs in the ambient network corroborated statistics for the NWIS data set in that median concentration of total iron is highest in samples from the Lower Pennsylvanian units, median concentration of dissolved sulfate is highest in samples from the Quaternary alluvium, and hardness and median concentrations of total nitrate plus nitrite are highest in samples from the Cambrian and Ordovician units. Data from the ambient network did not show any significant seasonal variations in groundwater quality. Of the additional constituents sampled for in the ambient network, median concentrations of metals were less than U.S. Environmental Protection Agency drinking-water standards, and organic chemical constituents were rarely detected.

Statistical comparisons of data from the NWIS data base and the ambient network data set showed no significant differences except for fecal coliform, iron, and manganese. Median concentrations of these three constituents were several times greater for samples from wells and springs in the ambient network. Statistical differences in values for these constituents could be attributed to differences in the state of constituents sampled (dissolved concentrations of iron and manganese for the NWIS data set as opposed to total concentrations for the ambient network data set) and the smaller number of sites in the ambient network. Statistical resolution could be improved by sampling a greater number of wells and springs that have a greater diversity of geologic and topographic conditions for the ambient network. The present ambient network does not include sites in Silurian or Middle Pennsylvanian geologic units nor sites in hilltop settings. The statistical validity of the ambient network could be improved by sampling additional sites, especially those for aquifers underrepresented in the data set.