With the coming rainy season, some Sonoma County residents are fearful of the effects of runoff from the recent North Bay fires entering the nearby Russian River, a major source of water for Sonoma and Marin counties.
Scientists at the Lawrence Berkeley National Laboratory are studying the fire’s impact on the Russian River and the groundwater system, which serves about 600,000 residents in Sonoma and Marin counties, according to an article published by the lab last week.
The fires, which began Oct. 8, burned more than 100,000 acres and destroyed more than 5,700 structures. Many UC Berkeley students hail from the affected area and were subsequently uprooted from their communities.
The lab is also working with the United States Geological Survey, or USGS, and Sonoma County Water Agency, or SCWA, to monitor water quality in Sonoma County, according to an SCWA press release published last month.
There are six riverbank filtration systems located along and around Sonoma County’s Russian River, according to Michelle Newcomer, a postdoctoral fellow in the Climate and Ecosystem Sciences Division at the lab.
These riverbank systems, which pump river water 20 meters underground to natural aquifers, use sediments and environmental aerobic microbes to filter the water, according to Newcomer.
Normally, the water seeps through the tiny spaces between grains of soil, and the microbes in the filtration systems consume carbon to help remove contaminants, Newcomer said. When rains wash over burned areas left by the fires, however, extra organic carbon from the ashes can enter the filtration system to be consumed by the bacteria.
According to Newcomer, the danger is that more carbon creates more microbes, as the carbon acts as food for microbes. An excess of microbes causes “bioclogging,” the blockage of the spaces in the sediment.
When bioclogging occurs, the flow of water to aquifers beneath the ground is “dramatically” reduced, so wells may not receive enough water, Newcomer said.
Currently, the lab is using statistics and modeling to determine the conditions under which bioclogging occurs and how ash might impact the flow of the water to collector wells, according to Newcomer. The lab also sends water and ash samples to USGS to be further analyzed.
SCWA is working with several local partners, including the City of Santa Rosa and Sonoma County, to protect against flooding and the spread of debris, pollutants and sediment into storm drains and rivers.
“It is critically important that ash, debris and other pollutants are prevented from entering stream systems to the maximum extent possible,” noted the SCWA press release.
Drinking water in the greater Sonoma County area is continually monitored and safe to drink, according to the press release.