PORTLAND, Ore. ( KOIN ) – A new study from the United States Geological Survey found recent wildfires in the Pacific Northwest led to an increase in mercury levels in some streams, raising concerns over harmful levels of mercury in water and fish.
During the study — as first reported by the Idaho Capital Sun — researchers took samples of soil, water, bugs, and aquatic vertebrate from 36 headwater streams in Oregon, Washington, and Idaho one year after they were burned from wildfires in 2021 and 2022.
After gathering samples from areas including the western and eastern Cascades, and Blue Mountains, researchers found levels of mercury and methylmercury — a toxic form of mercury — were 89% and 178% greater in burned watersheds compared to unburned watersheds respectively.
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While mercury is natural occurring and found in plants and soil, the researchers explained that wildfires destroy groundcover and roots. Layers of ash from fires can then lead to increased runoff and erosion of soil into streams, according to the study.