Disinfection Byproduct Levels Continue To Decline in Portion Of Kernville System

Operational changes addressing water system issue for 50 Kernville 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. Cal Water has been working with the State Water Resources Control Board’s Division of Drinking Water (DDW) to reduce elevated levels of the disinfection byproduct that occurred in 2016.

Runoff from winter storms in early 2016 contributed 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.

Compliance with the HAA5 standard is based on a running annual average of samples collected each quarter at dedicated sampling sites. In the third quarter of 2016, DDW approved Cal Water replacing an existing sampling site with a site that more accurately represents the water in the area. Water quality test samples collected in the second and third quarters of 2016 at these sampling sites were both under the maximum contaminant level (MCL) of 60 parts per billion. Due to higher test results at the original site in the first quarter of 2016, however, the average result over the past 12 months is over the MCL at 80 ppb. It is reduced from the running annual average in the second quarter, which was 87.8 ppb.

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, 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.

To lower the HAA5 levels, Cal Water crews have taken a multi-pronged approach in both the treatment plant and the distribution system. Crews have 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 treatment unit to remove the TOC, which is expected to go online in the coming months. Additionally, TOC levels in the Kern River are returning to the normal range, which will decrease the potential for HAA5 formation.

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