The collective North Bay wildfires have moved on from emergency response to the investigation and cleanup phases, as displaced individuals return to their homes to assess the damage done. Chemists and biologists are concerned that the most far-reaching damage won’t be visible to the naked eye. Ash from the fire could be rich with cancer-causing toxins like copper, lead, aluminum, and mercury, and all of those toxic chemicals could infect the northern California’s water and marine life via ash runoff into rivers that empty into the San Francisco Bay.
A new article this weekend from Wired’s Adam Rogers documents the chemical hazards of the ash in great detail, but notes how we cannot predict the spread of the ash or how much risk it poses. “No one knows how much,” Rogers wrote. “It’ll be full of heavy metals and toxins—no one knows exactly how much, and it depends on what burned and at what temperature. The ash will infiltrate soils, but no one’s really sure how or whether that’ll be a problem. And eventually some of it—maybe a lot—will flow into the regional aquatic ecosystem and ultimately the San Francisco Bay.”
What makes the North Bay fire ash uniquely hazardous is the amount of non-organic material it contains. Normal forest fires create a simple and fairly predictable caliber of ash. But the North Bay fires covered much more residential acreage, ergo many more automobiles, electronics, and lead paint-covered surfaces, and so its ash is expected to be particularly toxic.
“For how many structures that were burned in fairly small areas in these fires, I think that's a first-of-its-kind event,” says Geoffrey Plumlee, associate director of environmental health for the US Geological Survey. “The concern is, can they get it cleaned up before the heavy rains come?”
But it will be quite some time before we have any scope of the risks posed and damage done. Oregon State University forest ecohydrologist Kevin Bladon notes the 2002 Hayman Fire in Colorado produced 765,000 cubic meters of ash, which was still found in drinking water reservoirs more than four years later. “We’re anywhere from five years to 100 years in terms of the longevity of effects,” Bladon told Wired. “That really depends on the severity of the fire and our ability to get some vegetation re-established on site.”
“If there are burned materials sitting on the roads, that’s going to move very rapidly into waterways,” Bladon added. “We have no handle on that at all.”
Debris cleanup is underway, a joint operation between the federal and state arms of the EPA, the Army Corps of Engineers. But the arrival of the winter rains seen as a helpful development when the fires were still burning will likely foster water runoff that will introduce the toxins into our water systems.
“We’re all recognizing that this disaster was of such magnitude, the organization is unfolding,” Santa Rosa Water director Bennett Horenstein told Wired. “We’re approaching the wet weather season. There’s a small storm forecast for next week.”