Full Description

As part of the National Water-Quality Assessment (NAWQA) Program, the U.SGeological Survey (USGS) is conducting Source-Water Quality Assessments (SWQAs)to characterize the occurrence and concentrations of anthropogenic organic compounds ingroundwater withdrawn from selected aquifers used for water supply. SWQAs areintended to complement existing drinking water monitoring required by Federal, State,and local programs, which focus primarily on post-treatment compliance monitoring. Inthe first year, samples of source or raw water collected from about 15 production wells ineach of 11 study areas across the United States were analyzed for about 270anthropogenic organic compounds that include pesticides, pesticide degradates,polycyclic aromatic hydrocarbons, and volatile organic compounds (VOCs). Detection-frequency and concentration criteria developed from the results of these analyses wereused to select a subset of the initial 163 wells for sampling during the second year of thestudy. During the second year, samples of source water from 69 wells and of thecorresponding finished water were analyzed to characterize the extent to whichcompounds detected in source water are detected in finished water.Preliminary findings from the first year of sampling indicate that the five most frequentlydetected compounds were the pesticides metolachlor, deethylatrazine, and atrazine withdetection frequencies of 52, 42, and 37 percent, respectively, and maximumconcentrations of 3.6, 0.3, and 0.4 micrograms per liter, respectively; the pesticidedegradate alachlor ethane sulfonic acid, with a detection frequency of 33 percent and amaximum concentration of 0.6 micrograms per liter; and the VOC trichloromethane, witha detection frequency of 47 percent and a maximum concentration of 13.5 microgramsper liter. About 45 percent of the constituents analyzed for were detected at least once.Results from the second year of sampling, which focuses on comparing concentrations ofanthropogenic organic compounds in source water to concentrations in finished water,will enable NAWQA researchers to ascertain which compounds frequently found insource water are entering the communities' distributions systems and the concentrationsat which they occur. Includes abstract only.

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Edition: Vol. - No. Published: 11/01/2005 Number of Pages: 1File Size: 1 file , 650 KB