Disinfection Byproduct Levels Continue to Decline in Portion of Kernville System

Operational changes successfully addressing water system issue for 50 customers

Operational changes made in Cal Water’s Kernville water system continue to successfully decrease levels of haloacetic acids (HAA5) in the water that serves 50 customers in a small portion of the Kernville system.

Water quality test samples collected in the third and fourth quarters of 2016 at dedicated sampling sites were both under the maximum contaminant level (MCL) of 60 parts per billion. Compliance with the HAA5 standard is based, however, on a running annual average of samples collected each quarter at dedicated sampling sites. Due to higher test results in the first quarter of 2016, the average result over the past 12 months is over the MCL at 88.8 ppb.

Runoff from winter storms contributes to higher levels of naturally occurring total organic carbon (TOC) material in the Kern River water supply. Higher TOC levels contribute to the formation of disinfection byproducts during the treatment process, which is necessary to meet federal and state water quality standards, according to Local Manager Chris Whitley.

To lower the HAA5 levels, Cal Water crews have taken a multi-pronged approach in both the treatment plant and the distribution system. Crews adjusted the amount of disinfection used, modified storage tank levels to encourage turnover and decrease water aging in the system, and installed a pilot granular-activated carbon (GAC) treatment unit to remove the TOC. As initial sampling of the pilot treatment system shows it is effectively removing TOC, Cal Water will seek to install full-scale GAC treatment at the plant.

According to Whitley, this is not an immediate health risk for these 50 customers, but rather a concern when consuming water at levels above the MCL over many years. The affected area includes Oak Court, Oak Place, Juniper Drive, Alder Court, Spruce Avenue, Pine Drive (between Elm and Riovista only), and Grandview in Kernville. Water quality tests confirm that HAA5 levels for all other areas within the Kern River Valley District remain in compliance with the MCL.

“Protecting our customers’ health and safety has always been our highest priority,” Whitley said. “We are pleased to see continuous improvement and will keep working to bring the annual average, which was elevated due to stormwater runoff and water quality treatment, back into compliance.”