State study identifies communities with contaminated drinking water supplies

Posted in: Ground Water News, Water Contamination
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Article courtesy by Elizabeth Larson | February 15th 2013 | Lake County News

LAKE COUNTY, Calif. – A new study released by the state finds that hundreds of communities around California – including three areas in Lake County – rely on contaminated groundwater sources for their drinking water supply.

The State Water Resources Control Board report, required by AB 2222, found that between 2002 and 2010, 680 community water systems – out of 3,037 – serving nearly 21 million residents, relied on a contaminated groundwater source affected by one or more of 31 “principal contaminants,” with arsenic and nitrate among the most commonly detected.

The report emphasized that those water systems are being subjected to “comprehensive treatment” in order to make the water sources safe. “Although many water suppliers draw from contaminated groundwater sources, most suppliers are able to treat the water or blend it with cleaner supplies before serving it to the public.”

The California Department of Public Health reported that more than 98 percent of Californians on public water supply are served safe drinking water.

“Groundwater contamination remains a challenge, requiring effort by community water systems to ensure their customers are delivered water that is safe to drink,” said State Water Board Executive Director Tom Howard. “This report offers substantive data on the types of contaminants and the extent of groundwater contamination, while offering several options to improve water quality to those residents who need it most.”

Most of the 680 community water systems are located in the Southern California Inland Empire, the east side of the San Joaquin Valley, the Salinas Valley, and the Santa Maria Valley, with Kern, Tulare and Madera counties having the most community water systems with those issues, according to water board officials.

However, the report lists three affected water systems in Lake County: Sunrise Shore Mutual Water Co. in Lower Lake, found with high levels of aluminum; Corinthian Bay Mutual Water Co., located outside of the Lakeport city limits, which has high nitrate levels; and Cal 20 Village in Upper Lake, where high methyl tertiary butyl ether levels were found.

Leah Walker, chief of CDPH’s Division of Drinking Water and Environmental Management, said the agency has regulatory oversight of all public water systems in Lake County. She said they have closely monitored these three water systems and worked with them to ensure the water they are delivering to their customers meets California drinking water standards.

She said CDPH regularly reviews water quality data from each system listed in the report and has conducted inspections of all three listed Lake County water systems.

Walker reported that Cal 20 Village has effective treatment for MTBE in the form of granular activated carbon filters.

The water system tested its finished water on a monthly basis during the eight-year time period covered by the report and no MTBE was detected in the finished water. “As such MTBE does not present a health issue in this public water system,” she said.

With Sunrise Shore Mutual Water Co., the system has naturally occurring aluminum in the water from its well. Over the years the water system has drilled several different wells to try and alleviate this issue, Walker said.

The system’s current well, well No. 3, was drilled in 2004. In 2008 the water system installed treatment to reduce iron and manganese in its source water. Walker said this treatment also has reduced the aluminum levels in the finished water.

Since December 2009, the water system has been monitoring its treated water for aluminum concentration on a monthly basis, and of the 32 samples recorded in CDPH’s database, four have exceeded the aluminum level of milligram per liter, Walker said.

At the same time, the average values have not exceeded the drinking water standard and the water produced by Sunrise Shore does not present a health issue to its customers, she said.

Regarding Corinthian Bay Mutual Water Co., Walker said it was the system’s well No. 1, a standby well, that surpassed the nitrate drinking level standard of 45 milligrams per liter, and therefore CDPH directed the water system to remove the well from service, according to Walker.

She said the water company did just that, then redrilled and installed a deeper seal. Since that time the well has produced water with no detectable nitrate.

The system’s other well has produced water with a very low level of nitrate. However, Walker said the drinking water delivered to customers from these wells does not exceed the drinking water standard and does not present a health issue to its customers.

Walker said CDPH continues to monitor the three water systems and will take additional action if values in the drinking water exceed the respective standards.

In releasing the report, the water board cited a US EPA estimate that California will need $40 billion during the next 20 years for infrastructure development and improvements to ensure the delivery of safe drinking water.

Email Elizabeth Larson at . Follow her on Twitter, @ERLarson, or Lake County News, @LakeCoNews.

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