There is now plenty of evidence that as the atmosphere warms, the planet is experiencing more wildfires. The fires still sweeping huge swaths of Australia are the most striking example, but in many other regions the fire season is also growing longer. Understandably, much of the media surrounding these incidents focuses on the immediate damage to forests, homes, people and wildlife, but one potentially dangerous long-term impact has received less attention – the effect of fires on water.
Newsha Ajami, a hydrologist and director of urban water policy at Stanford University has been taking a closer look at this issue. As a member of the San Francisco Regional Water Quality Control Board, she knows the risks all too well. In 2019 there were 6,872 fire incidents in California, burning more than 253,321 acres with 732 structures damaged or destroyed. ‘After a few of these wildfires, especially the ones that had an interface with urban areas, we had to think about clean-up very quickly, before rain storms hit, to make sure that the water wouldn’t carry all the metals, contaminants and pollutants out to the waterways,’ she says.
The irony is that the very thing most people are hoping for in fire incidents – rain – makes the situation worse when it comes to water quality as storms can wash the residue of burned objects into streams and rivers. Ajami notes that fires that cross into urban areas are of particular concern because so many of the items used in homes and industries – from fridges and computers to batteries and paint – contain potentially toxic chemicals and heavy metals. In addition, the chemicals used to tackle fires can also be problematic. Studies have shown that commonly used fire retardants can be lethal to aquatic life. Another issue is that fires often damage water infrastructure. In 2018, one Santa Rosa neighbourhood discovered that fires from the previous year had led to melting water pipes and benzene contamination (a carcinogen) of the water supply.
Luckily, Ajami says that most of the 2019 fires in California were contained before the rains came, with teams cleaning up as fast as possible and placing barriers to stop the storm carrying sediment with it. But she notes that better management plans need to be in place for future fires. She also adds that in the face of increasing wildfires we need to start pursuing preventative action to protect water supplies.
‘The more we work with nature, the better it is,’ she says. ‘We should try to depend more on natural materials and try to create spaces or zones that would prevent fire getting too close to urban areas. You can also do prescribed burns, which means trying to burn a little bit of the forest in a very controlled way to prevent it leading to these massive fires.’
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