Baykeeper Update

Toxic Ash from North Bay Fires Poses a Threat to the Bay

The devastating wildfires that swept through Napa and Sonoma last month have caused unprecedented damage to families, homes, and businesses. Unfortunately, the disaster also poses a new threat to San Francisco Bay in the form of toxic ash washing into local rivers and creeks that drain to the Bay.  

More than 8,000 residential homes—in addition to commercial buildings and other structures—were destroyed by the North Bay wildfires. Many of these buildings contained potentially hazardous substances. Most households, for example, have electronics, plastics, and furniture treated with chemicals, along with toxic substances that include solvents, cleaning supplies, and pesticides. Older homes might also be contaminated with asbestos and lead paint. These materials were incinerated during the fires and mixed with fire-fighting chemicals to create toxic ash.

As winter rains begin in earnest, and rain water flows through charred sites, this ash will be washed into storm drains and streams that feed into Napa River and Sonoma Creek. These waterways flow into San Pablo Bay and its surrounding wetlands in the northern part of San Francisco Bay.

Contaminated ash from the fires will potentially affect wildlife and nearby shoreline communities. The threat is particularly high for creatures living in the San Pablo Bay National Wildlife Refuge, which lies at the confluence of North Bay tributaries and San Pablo Bay. It may take many years for the ash to make its way through the North Bay watershed and be flushed out from the ecosystem.  And depending on the toxicity of the ash, it could have lasting harmful impacts on the Bay’s wildlife.

The Environmental Protection Agency (EPA) and other government agencies have begun surveying damaged areas for toxic materials and collecting hazardous items such as charred propane tanks to clear the way for ash removal. Homeowners are also beginning to clear and contain burned materials. These efforts are critical to limiting the damage to the surrounding environment. Baykeeper will continue to monitor impacts to the Bay from toxic ash runoff.

For more information about hazardous waste cleanup and debris removal in fire-affected areas, please visit the California wildfires recovery website.

Photo by the California National Guard