Home News UC Santa Cruz researchers study impacts of CZU wildfires on local streams

UC Santa Cruz researchers study impacts of CZU wildfires on local streams


After the CZU Lightning Complex fires tore through the counties of San Mateo and Santa Cruz in 2020, over 86,000 acres of land were left ravaged in its wake. Now, scientists from UC Santa Cruz are looking into the aftermath of the wildfires in nearby watersheds.

One month after the fires, coastal hydrologist Christina Richardson organized a team and scoured the mountains to assess any variance in the stream water composition. They spent over two years taking samples and analyzing water chemistry across four different sources: San Lorenzo River, Laguna Creek, Majors Creek and Scott Creek. The post-fire results were then compared with pre-fire data obtained from partnerships with organizations such as the Santa Cruz Water Department.

“With climate change, wildfires are becoming more common,” said Richardson. “There’s just a paucity of pre-fire data that has impaired our understanding of how fires are actually impacting stream water composition. And because streams are often used for drinking water, this is particularly important to understand.”

The study measured around 40 different components present in the streams, though did not find changes that would be considered harmful to humans. Even so, Richardson says the results are telling: the water chemistry is altered by wildfires, and a diverse range of chemicals can enter varying streams. Each watershed displayed a different response that could have depended on multiple factors, such as rainfall characteristics and topography.

“The one special thing about that specific research is we had all sorts of measurements in the same streams and rivers before the fire, so we can directly link the changes to the fire,” said Adina Paytan, a UCSC professor who works with Richardson in her biogeochemical lab.

Allison Myers-Pigg, an environmental scientist from the Pacific Northwest National Laboratory, particularly praises the work for its comprehensive and unique dataset. She points out the difficulty in designing a study around a disturbance event, and Richardson’s rapid response helped capture immediate and long-term impacts.

These impacts not only influence the composition of stream water but could affect aquatic wildlife as well. “There’s been a lot of attention on the effects of wildfire on terrestrial ecosystems (and) a lot less work done on aquatic ecosystems, even though they certainly will experience responses to wildfire,” said UCSC professor Eric Palkovacs.

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