EPA Orders Solano Irrigation District to Remove Chemical From Drinking Water

May 12, 2005

The U.S. Environmental Protection Agency recently ordered the Solano Irrigation District to reduce levels of disinfection byproducts from drinking water treated by the district’s Gibson Canyon water system.

The EPA promulgated new 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. This is the first action taken by the EPA against a small water system in California under the agency’s disinfection byproduct regulation.

"Chemical byproducts in treated drinking water need to be monitored, reported and reduced to meet federal health standards," said Alexis Strauss, the EPA’s water division director for the Pacific Southwest region. "In this case, the district notified the public and has begun changing their operations to prevent the byproduct from forming."

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 ppb; the Gibson Canyon system had a range from 98 to 107 ppb. While the system exceeds the standard, no effects on human health are anticipated from this short-term exposure.

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

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 January 1, 2004 to March 31, 2005.

The order requires the district to submit a compliance plan within 21 days of receiving the order and to reduce disinfection byproducts to below federal standards no later than September 30, 2006.

The EPA has worked closely with the California Department of Health Services which administers most of the Safe Drinking Water program in the state. However, the state has not yet obtained primary enforcement responsibility for the new byproduct regulations.

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

Source: U.S. Environmental Protection Agency