Upcoming rain spurs concern about Sonoma County water contamination from toxic ash

The specter of rain washing potentially toxic ash from thousands of burned homes into sensitive Sonoma County watersheds has injected a new sense of urgency to local fire cleanup efforts, with the immediate focus shifting to erosion control needed to safeguard water quality.

The risk comes at the outset of a historic government-funded debris removal program in the region, where the largest and most destructive wildfires that broke out Oct. 8 were finally brought under full containment Tuesday.

With rain in the forecast for Friday and next week, the health of the local watersheds, including 617 streams in fire-affected areas, has become a top priority, officials said.

“We consider it a very high threat,” said Mona Dougherty, a senior water resource control engineer with the North Coast Water Quality Control Board in Santa Rosa. “We are very concerned about the impacts to aquatic life and drinking water.”

The Tubbs and Nuns fires wiped out nearly 7,000 Sonoma County structures, including 2,900 homes in Santa Rosa alone.

Ash and debris from incinerated homes can contain numerous hazardous materials, including asbestos, heavy metals, by-products of burned plastics and other chemicals, according to the Sonoma County Department of Health Services.

While direct human contact with this material poses health risks to humans, the material also poses dangers to waterways, which feed local drinking water supplies and provide valuable habitat for a variety of species, including endangered salmon.

“Drinking water is safe and continually monitored, but because the county’s natural watersheds filter drinking water, it is critically important that ash, debris and other pollutants are prevented from entering stream systems to the maximum extent possible,” stated a joint press release from Sonoma County, the Sonoma County Water Agency and the city of Santa Rosa.

The Water Agency provides Russian River drinking water to 600,000 North Bay residents from Windsor to northern Marin County.

Local governments and other agencies have banded together in a taskforce to ensure measures are in place to prevent harmful runoff into creeks and rivers, said Rita Miller, deputy director of environmental service for Santa Rosa Water. The group’s first meeting was Monday.

To date, Santa Rosa city public works crews have placed 1,500 to 2,000 gravel bags around storm drains in Coffey Park, as well as straw bale weirs in the Fountaingrove area, Miller said.

While those gravel bags might not do much to remove or neutralize toxins and heavy metals, additional wattles with organic material designed to do just that will be added as soon as possible, she said.

The hope is that the upcoming rains will be modest, Miller said.

“We’re super grateful that this rain looks like is to going to be a light to moderate soaking that hopefully will not produce a lot of runoff,” Miller said.

About a quarter of an inch of rain is forecast for Friday evening, with more possible on Sunday, according to AccuWeather. Since Oct. 1, Santa Rosa has received a paltry 0.21 inches, compared to more than 7 inches last year at this time.

Doug Allard, owner of The Wattle Guys, said local water quality officials “have been having a hell of a time getting the wheels moving” but now they seem to have begun taking the threat seriously.