Disinfection By-Products Maximum Contaminant Level (MCL) Exceedance for Disinfection By-Products (DBPs) in the Ebbetts Pass Distribution System
DBPs are formed in the water system when chlorine used in the disinfection process reacts with naturally occurring total organic carbon (TOC – formed by the decomposition of plant matter). TOC is difficult to remove by filtration at the water treatment plant and chlorine is a powerful disinfectant that provides a measurable disinfectant residual. By law, CCWD is required to have a measurable chlorine residual at all times throughout the water system. DBPs are regulated by the State in parts per billion. It is suspected that prolonged exposure to large volumes of DBPs over a long period of time can cause cancer. As a result, the State has placed Maximum Contaminant Level requirements on two families of DBPs. These are Total Tri-halomethanes (TTHMs – 80 parts per billion) and Haloacetic Acids (HAA’s – 60 parts per billion).
The Calaveras County Water District is required to take quarterly DBP monitoring samples from multiple sites throughout the Ebbetts Pass Service Area (4 – 16 sites). For each location, CCWD is required to maintain a running annual average of the sample results. CCWD cannot exceed the MCL for either constituent at any sample site.
In the fourth quarter of 2020, CCWD exceeded the Locational Running Annual Average (LRAA) Maximum Contaminant Level (MCL) for HAA’s at one sample site within the Ebbetts Pass System. The MCL is 60 parts per billion and the District’s LRAA exceedance was 61 parts per billion.
The Ebbetts Pass water system recently failed a drinking water standard. Although this is not an emergency, as our customers, you have a right to know what you should do, what happened, and what we are doing to correct this situation. This one sample result MCL exceedance is not representative of the water quality for the entire water system.
Notification letters were mailed to all Ebbetts Pass service area customers on February 10, 2021. The following documents were included in the mailers:
CCWD VIRTUAL TOWN HALL MEETING
CCWD will be hosting a virtual town hall meeting on February 23, 2021 at 6:00 pm. We encourage anyone with questions or concerns to attend. You can view the full town hall meeting announcement here.
For more information on DPBs please visit our Disinfection Byproducts webpage.