BOISE, Idaho — There are pretty obvious results of wildfires across Idaho and the Northwest, burn scars are maybe the easiest tell. Other impacts are not really visible to the human eye.
Austin Baldwin, a research hydrologist at the Idaho Water Science Center, is part of a research team that found quite a story—a link between wildfires and increased mercury concentrations in Pacific Northwest headwater streams.
He said the wildfires in the west are getting worse, leading to the increase.
“Mercury gets into the water because mercury is deposited from the atmosphere that accumulates in the soil. It binds to the soil particles. And so if there's a snowmelt or rain, that soil gets washed into the stream. And then it's in the stream and available to organisms, to fish. With a fire, you burn away all that underbrush, so you have more erosion of soil into the stream,” Baldwin said.
The research looked at levels a year after a fire.
“Higher mercury concentrations in the burned watersheds, and in some of the stream invertebrates in those watersheds. The concentrations were not extremely higher, but they were definitely higher,” Baldwin said.
But, he stresses that even though invertebrates were found with higher levels of mercury, it affects the food chin.
“Fish have a long, a long lifespan to accumulate mercury and a lot of lower organisms that it accumulates it from. So if you eat like a catfish, which doesn't eat other fish, they don't accumulate a lot of mercury. But like a bass or a tuna, would accumulate a lot of mercury,” Baldwin said.
So, the concern here hinges on the fact that wildfires continue to get worse in the West, allowing mercury to travel more into headwater streams, and issues from there head downstream.
“So, for example, lakes and reservoirs downstream, if they're receiving more mercury from headwater areas, then top predator fish, sport fish, in those lakes and reservoirs are likely going to accumulate more mercury in them, which could be a health concern for people who are eating a lot of those fish,” Baldwin said.
This isn’t a news story telling you to stop eating fish right now or forever. But, if wildfires do continue to get worse this research shows just one impact of it.
“With increasing wildfires frequency and severity we could see this being more and more important. And so it could be a scenario of, instead of eating a fish a week, maybe a fish every other week from, from certain places,” Baldwin said.