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The original item was published from 3/3/2021 2:03:46 PM to 3/26/2021 3:21:02 PM.

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Posted on: March 3, 2021

[ARCHIVED] City Switching to Lake Hennessey for Water Supply for Three Weeks

Lake Hennessey

The City recognizes the changing aesthetics of the drinking water, which is common with surface water supplies. Starting on March 5th our State Water Project supply source (Delta water) will be unavailable for three weeks to perform maintenance which necessitates using our Lake Hennessey water. 

The taste and odor is not unique to Napa’s water sources - seasonal algae blooms are common to many surface waters. As algae dies off they release odor causing compounds.  Most persons describe the aesthetics of this phenomenon as earthy and/or musty. The water treatment process removes the algae, although compounds that cause an unpleasant odor can be detected as low as 3 nanograms or parts per trillion by the average person. The drinking water, while potentially aesthetically undesirable, is tested and verified safe to drink.

As part of a $45-million upgrade of the treatment plant that treats Delta water, an ozone system was added that helps control the taste and odor. An ozone system or similar best available technology (BAT) treatment train is in the early stages of planning for the Hennessey Water Treatment Plant. For now, a few ways to minimize the odor when drinking water direct from your tap is: 

•        make sure it is cold, or 

•        add a squeeze of citrus (lemon, lime, orange) or cucumber.

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