Samples taken from key Russian River tributaries downstream of the massive Tubbs fire scar have so far tested within the expected range for a suite of 30 pollutants and other traits that might betray contamination related to ash, burned wreckage and recent firefighting efforts, according to North Coast water regulators.
The results are just the earliest in the long-term monitoring planned for the 1,500-square-mile river watershed. Scientists want to ensure that critical water supply and wildlife habitat aren’t exposed to heavy metals, excess sediment and other pollutants potentially leached from thousands of burned structures, vehicles and unknown materials incinerated in the October firestorm.
Staff with the North Coast Regional Water Quality Control Board also caution that the results reflect a limited number of test sites — three from below the burn zone and one from above.
But the outcome of three testing rounds conducted last month nonetheless contributes to faith in the success of a multiagency, all-hands-on-deck effort to deploy more than 30 miles of straw erosion-control wattles and tens of thousands of gravel bags to filter runoff from winter rains and direct it away from storm drains and streams, Senior Environmental Scientist Katharine Carter said.
She’s hoping, she said, that follow-up testing and city and county water quality work will supply additional proof of the work’s effectiveness.
Testing from Nov. 1, before heavy rain hit; Nov. 8, right after a 1-inch rainstorm; and Nov. 15, after 2 inches of rain fell produced test results consistent with historic samples from 2004 to 2011 without spiking “above what we would normally see in rain events of this magnitude.”
The October fires charred a combined 137 square miles in Sonoma County, burning more than 6,500 structures, mostly homes, and leaving a hazardous melange of metals, chemicals and other materials on the landscape.
Heavy metals like aluminum, arsenic and chromium have been of particular concern, as well as byproducts of pesticides and other household hazardous materials. Also, heavy use of fire retardants to try to slow the fires’ spread means the landscape was covered with nitrogen and phosphorous, the main ingredients in retardants, as well as other chemicals, depending on the brand.
The U.S. Environmental Protection Agency took on the first round in assessing and removing hazardous objects from burned housing sites within the perimeters of the various fires, followed by contracted experts who are currently clearing ash and rubble site by site.
But the scale of the fires means the work needed to monitor and address potential problem sites will go on for some time, provided grants and other funding can be identified, officials said.
The initial testing conducted last month was a start, involving sample sites on upper Mark West Creek, near Leslie Road at Porter Creek Road; and lower Mark West Creek, at Fulton Road; as well as Piner Creek, at Marlow Road; and Santa Rosa Creek, at Willowside Road.
Samples from each site were tested for 30 qualities, like acidity and turbidity, as well nitrogen, mercury, lead, sulfate and many other contaminants.
In addition, officials used a tiny crustacean called an amphipod, a water flea, and a fathead minnow to further test the water to see if any additional substances har to aquatic wildlife might be detected, said Rich Fadness, coordinator of the Surface Water Ambient Monitoring Program with the North Coast board. All were negative.