There is an air filter for your car, a filter for your tap water, and air filters for our smoky Northwest air. Now, there could be a filter to help the region’s struggling salmon.

According to a new study from Washington State University, using simple biofilters on stormwater runoff can dramatically increase the survival rate of newly hatched coho salmon.

“This study highlights how vulnerable the fish are as soon as they hatch to the toxic impacts of stormwater runoff,” said lead author and associate WSU professor Jen McIntyre. “Biofiltration appears to be very effective at preventing that acute lethal toxicity. We also found that it prevented some of the sub-lethal effects, but not all of them.”

The effects of chemical-carrying stormwater runoff from roads, and other places, into streams and rivers has recently received a lot of attention. After years of searching for the cause of so many salmon deaths, researchers discovered in 2020 that a tire stabilizer (6PPD) breaks down into a toxic substance. As tires wear down on the road, their rubber, and all the chemicals they carry, wash into local bodies of water where fish and wildlife encounter them.