U.S. Geological
Survey
Open-File Report 01-271
Online Version 1.0
By Tamara Ivahnenko, Stephen Grady, and Gregory Delzer
The U.S. Geological Survey (USGS), in collaboration with the Metropolitan Water District of Southern California (MWDSC) and the Oregon Graduate Institute of Science and Technology (OGI) in Beaverton, Oregon, is designing a survey of the frequency of detection, concentration, and distribution of methyl tert-butyl ether (MTBE), other ether gasoline oxygenates, their degradation products, and other volatile organic compounds (VOCs) in source water used by community water systems (CWSs) in the United States. This national survey is sponsored by the American Water Works Association Research Foundation.
The survey will be accomplished in two stages. The first stage, termed the Random Source-Water Survey, will determine the frequency of detection and the range in concentrations of MTBE, three other ether gasoline oxygenates, and 62 other VOCs in drinking-water sources through a statistically stratified design for sampling CWSs by the total number of systems within five population served-size categories, source of water (ground or surface water), and the total number of people served by each of the source-size categories presently used within the United States. A total of 1,000 CWSs that will represent the more than 54,000 CWSs from all 50 States, Native American Lands, and Puerto Rico will be sampled. The 1,000 source-water samples will be distributed to allocate 613 samples to ground-water-supplied CWSs (wells, springs, and galleries) and the remaining 387 samples to surface-water-supplied CWSs (rivers, aqueducts, canals, lakes, and reservoirs). Environmental samples and field blanks will be collected by CWS personnel. Samples will be analyzed by the MWDSC using U.S. Environmental Protection Agency approved method 524.2. Ancillary information about the participating CWSs and their sources will be collected to allow additional statistical analysis of the water-quality data.
The second stage, termed the Focused Source-Water Survey, will be based on factors that appear or are known to be related to frequent detection of MTBE and other VOCs in source water. CWSs located in hydrologic, climatic, and/or demographic settings that are suspected or known to be vulnerable to MTBE contamination will be selected for sampling. Large CWSs that have source water suspected of having concentrations of MTBE, are located in 14 metropolitan areas with populations greater than 250,000, and use reformulated gasoline (RFG) will be selected initially. States not located in RFG areas may also have areas with a high detection frequency of MTBE in ground water at regulated gasoline release sites. Discussions with drinking-water officials, water suppliers, and USGS personnel will provide a better understanding of the risk of MTBE releases to source water in these States. Additional suspected source waters will be identified through these discussions.
Data on samples of source water with known concentrations of MTBE will be obtained from recently completed or ongoing sampling activities, including the Random Source-Water Survey, and from water-quality monitoring in individual States. Approximately 480 samples will be collected from 80 wells, 40 reservoirs, and 20 rivers across the United States. All samples in the Focused Source-Water Survey will be collected by USGS personnel using USGS sampling protocols. Samples for the Focused Source-Water Survey will be analyzed by the MWDSC for MTBE, three other ether gasoline oxygenates, and 62 other VOCs. Duplicate samples will be collected with about one-half of the Focused Source-Water samples and analyzed for oxygenate degradation products by OGI. As with the Random Source-Water Survey, ancillary information for the Focused Source-Water Survey will be collected to allow additional statistical analysis of MTBE and other VOC data.
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