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Press Release

Friday, February 16, 2018

Post Date:02/16/2018 3:02 PM


Calistoga City Seal

City of Calistoga


For Immediate Release
February 16, 2018

Contact: Mike Kirn
Public Works Director
(707) 942-2828

Improved water quality for disinfection by-products in Calistoga’s drinking water.

Over the last few months the City has issued two notifications because certain disinfection by-products exceeded limits established by the Department of Water Resources – Division of Drinking Water. Disinfection byproducts are common byproducts from chlorine reacting with naturally occurring organics in the water during the disinfection treatment process.

Trihalomethanes, or THMs, and haloacetic acids, or HAAs, are measured monthly and a four quarter average is determined for compliance monitoring. The limit for THMs is 80 parts per million (ppm) and the limit for HAAs is 60 ppm.

Despite those exceedances, Public Works staff routinely works aggressively to reduce the amount of disinfection by-products in Calistoga’s drinking water. We are in regular communication with the State Water Resources Control Board - Division of Drinking Water, we have engaged the services of a specialist in water chemistry and have selected an outside consultant in the water treatment industry to assist the City in identifying economical measures for removal/reduction of disinfection by-products.

To access the effectiveness of its efforts, the City took additional samples in December and January at the sampling sites near the Calistoga Public Library and on Greenwood Ave. at Grant St. In December, samples from the Library site showed THM results were 28.3 ppm and HAAs were 44.3 ppm. The same month, samples at the Greenwood Ave. location showed THMs were 54 ppm and HAAs were 50 ppm – all under the state limit. For January 2018, at the Greenwood Ave. site the THMs were 30 ppm and HAAs were 37 ppm, again below the state limit.

The reduction in disinfection by-products over the past two months is encouraging and demonstrates efforts have resulted in the reduction of the formation of disinfection by-products. However, because the City is required to use the test results from the prior three quarters, it is possible that the City’s four quarter running average may again be above the state limit. If that is the case, the City would be required to issue another notice of exceedance. Please be assured the City is doing everything it can to improve water quality and we appreciate your patience. If you have any questions please call us at 707-942-2828.


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