• Low levels of certain man-made chemicals remain in public water supplies after being treated in selected community water facilities
RESTON, VA, Dec. 5, 2008 -- Water from nine selected rivers, used as a source for public water systems, was analyzed in a study by the U.S. Geological Survey (USGS).
"Most of the man-made chemicals assessed in the USGS study are unregulated in drinking water and not required to be monitored or removed," says Tom Jacobus, General Manager of the Washington Aqueduct. "These findings are not surprising and they will be important in helping regulators and assisting water utility managers arrive at decisions about future water treatment processes."
Scientists tested water samples for about 260 commonly used chemicals, including pesticides, solvents, gasoline hydrocarbons, personal care and household-use products, disinfection by-products, and manufacturing additives. This study did not look at pharmaceuticals or hormones.
Low levels of about 130 of the man-made chemicals were detected in streams and rivers before treatment at the public water facilities (source water). Nearly two-thirds of those chemicals were also detected after treatment. Most of the chemicals found were at levels equivalent to one thimble of water in an Olympic-sized pool.
"Low level detection does not necessarily indicate a concern to human health, but rather indicates what types of chemicals we can expect to find in different areas of the country," said USGS lead scientist, Gregory Delzer. "Recent scientific advances have given USGS scientists the analytical tools to detect a variety of contaminants in the environment at low concentrations; often 100 to 1,000 times lower than drinking-water standards and other human-health benchmarks."
Testing sites include the White River in Indiana; Elm Fork Trinity River in Texas; Potomac River in Maryland; Neuse River in North Carolina; Chattahoochee River in Georgia; Running Gutter Brook in Massachusetts; Clackamas River in Oregon; Truckee River in Nevada; and Cache La Poudre in Colorado. The populations in communities served by these water treatment plants vary from 3,000 to over a million.
This study is among the first by the USGS to report on a wide range of chemicals found before and after treatment.
>> Get the full source-water quality assessment and listing of chemicals are available online.
The USGS National Water-Quality Assessment Program is planning to complete as many as 21 additional surface-water assessments through 2013. A companion study is scheduled for release in 2009 that summarizes the occurrence of the same chemicals in high-production wells and the associated treated water in 13 states.
USGS provides science for a changing world.
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