Testing the Link Between Wildfires and Benzene Contamination

In the weeks following the Santa Rosa, CA wildfires last October, city officials found elevated levels of benzene in water system samples taken from the nearly totally-razed Fountaingrove neighborhood. The first round of samples returned 4 results of over 500 parts per billion, with one of these at 918 parts per billion (MCL for benzene in drinking water is 1 part per billion). A second round of testing produced similar numbers over the MCL, without the higher spikes. A total of 145 samples have now shown elevated levels.

According to this article in The Press Democrat, city officials, who for months have stressed that the contamination appeared isolated to the advisory area, were taken by surprise that six of those results were from outside the existing advisory area.

With the help of a forensic chemist, who helped eliminate the possibility of petroleum leaks, the city now suspects that the most likely cause of contamination is heat damage to high-density polyethylene service lines or other plastic components (such as PVC) in the water or wastewater system. The city is enacting more extensive testing to find out if plastic laterals are responsible. Once the exact cause is identified, the city will consider solutions. Replacing the water system could cost over $20 million.

Interested in finding out more about benzene contamination in drinking water supplies, including sampling methods, treatment strategies, and private well concerns? Check out this EPA website or this Oregon Health Authority factsheet. Another useful resource is this template (from North Carolina) to be used when high levels of Benzene need to be reported to the public.

The Unique Challenges of Wildfires for Water Systems

Recent wildfires in California’s Sonoma and Napa Counties have caused loss of life and significant damage not only to over 5,700 homes and businesses, but also to critical water infrastructure in the region.

In Santa Rosa, residents have been instructed to use only bottled or boiled water for drinking and cooking. According to the city's water engineer, the system is currently experiencing unusually low water pressure, due either to high volumes being used by firefighters or damage to infrastructure. She explains that when water pressure drops below a certain level, backflow prevention devices – particularly in the higher elevations of the system – many not work properly.

Loss of pressure is only one of the many unique and harmful effects wildfire can have on water systems. This 2013 Water Research Foundation report on the effects of wildfire on drinking utilities lists many more, especially the dramatic physical and chemical effects on soils, source water streams and water quality that would necessitate changes to treatment operations and infrastructure. In fact, according to the US EPA, long-lasting post-fire impacts (especially flooding, erosion and sedimentation) can be more detrimental to water systems than the fire itself. 

The WRF report also suggests mitigation and preparedness strategies for utilities, including using fire behavior simulators to identify areas to target for fuel reduction activities, such as this goat grazing program in California. The idea behind such collaborative programs is that the less vegetation fuel available for fires to consume, the better. 

The increase in wildfire incidents such as these across the country make it all the more important for water systems of all sizes to be prepared for the unique challenges of wildfires. A good way to start your preparation is by checking out WaterOperator.org’s listing of free wildfire resources by typing in the word “wildfire” in the search box.

No time to lose? The US EPA has a page of "rip & run" resources including this Wildfire Incident Action Checklist.