Central California Water District Ordered To Remove Chemical From Drinking Water

On Dec. 20, 2005, EPA ordered the Groveland Community Services District in Tuolomne County, Calif., to reduce levels of disinfection byproducts from the drinking water it provides to customers.

In this case, the byproduct chemicals are detectable in very trace amounts. EPA does not suggest that customers need alternative or bottled water.

"Chemical byproducts in treated drinking water need to be monitored, reported and reduced to meet the federal health standard," said Marvin Young of the EPA's Drinking Water Office in the Pacific Southwest region. "In this case, the district notified the public and has begun changing their operations to prevent the byproduct from forming."

The byproduct chemicals detected in the district's water system are total trihalomethanes and haloacetic acids, which after many years of consumption may cause some people to experience liver, kidney or central nervous system problems and may increase the risk of cancer.

While the system exceeds the standard, no effects on human health are anticipated from this short-term exposure, agency officials said.

Although detected in trace amounts over the federal drinking water standard, the district is required to notify the public when detection goes above health-based standards. The drinking water standard for total trihalomethanes is 80 parts per billion (ppb); the Groveland system had a range from 126 ppb to 142 ppb. The drinking water standard for haloacetic acids is 60 ppb; the Groveland system had a range from 75 ppb to 110 ppb.

The district was required to monitor its water system for these chemicals on a quarterly basis beginning January 2004. The district violated the standard from Jan. 1, 2004, to Sept. 30, 2005, and the violations are expected to continue until new treatment processes are built.

The order requires the district to submit a compliance plan -- including a treatment construction schedule -- within 21 days of receiving the order and to reduce disinfection byproducts to below federal standards no later than Sept. 30, 2008.

EPA approved disinfection byproduct regulations in December 1998 to protect public health from potentially harmful byproduct chemicals formed when chlorine reacts with natural organic compounds during the treatment process (see http://www.epa.gov/OGWDW/mdbp/dbp1.html for additional information).

The Disinfection and Disinfection Byproduct rule began regulating surface water systems serving 10 thousand or more customers in January 2002. Phased implementation of smaller surface systems as well as groundwater systems began in 2004.

This is the third action taken by EPA against a small water system in California under the agency's disinfection byproduct regulation. The Groveland Community Services District serves as many as 9,000 customers in Groveland, Big Oak Flat and Pine Mountain Lake.

Additional information on trihalomethanes and haloacetic acids can be found at http://www.epa.gov/enviro/html/icr/gloss_dbp.html.

This article originally appeared in the 01/01/2006 issue of Environmental Protection.