Wildfires pose threat to Napa and Sonoma drinking water

Friday, Oct 27, 2017

By Elizabeth Zach, RCAC staff writer

Fortunately none of the Napa and Sonoma Counties ravaged by wildfires during October are without drinking water. However, water regulators say that treating drinking water may be a challenge as they work to mitigate ash and erosion around reservoirs.

Regulators point to the 2015 Valley Fire in neighboring Lake County. It burned in the Putah Creek watershed and nearly two years later water systems serving the small, rural communities of Berryessa Estates and Berryessa Highlands found ash residue from the fires.

“Once it came, it was goo,” Phillip Miller, engineer for the two water systems, told the Napa Valley Register newspaper. “Ash is a very, very fine material.”

The city of Napa relies on the Milliken Reservoir, which is dirtier following the Atlas Fire, according to water authorities. The fires’ blaze reached the reservoir and the watershed is charred and burned, which makes erosion more likely. Ash also fell in the water.

“(Ash) is an organic carbon,” Napa’s City Water General Manager Joy Eldredge told the Register. “Those are the things we try to remove through our treatment process.”