Hotter and drier conditions driven by climate change are leading to an increasing number of wildfires in North America and around the world. The damage wildfires cause – to forests, homes, and communities – is well-known. But long after the flames are gone, the effects can linger, especially in rivers and streams, where water quality may suffer for years.
A new study by scientists at the CIRES institute at the University of Colorado Boulder analyzed more than 100,000 water samples from more than 500 sites across the Western U.S. and found that wildfires can degrade water quality for up to eight years after a fire. The research, which was recently published in the journal Nature Communications Earth & Environment, found elevated levels of organic carbon, nitrogen, phosphorus, sediment, and turbidity – the cloudiness of water – in basins affected by fire.
This large-scale analysis reveals watersheds take longer to recover from wildfires than previously thought, with widespread, long-lasting impacts often going undetected for years.
Organic carbon, phosphorus, and turbidity remain elevated for one to five years after a fire. Nitrogen and sediment levels stay notably high for up to eight years. Fire-driven impacts are worse in more forested areas.
Each watershed in the study responded differently depending on local conditions. In some places, sediment levels surged to as much as 2,000 times normal levels, while others remained relatively unchanged.
The research team hopes its findings can help guide future planning efforts to improve wildfire resilience.
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Wildfires threaten water quality for years after they burn
Photo, posted April 6, 2017, courtesy of Bonnie Moreland via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio