By Phuong Le
Stormwater runoff that results from everyday activities — oils from leaky cars, pesticides from lawns and other pollutants — killed fish within four hours in a recent study. The salmon were fine when the same water was filtered through a simple mixture of gravel, sand and compost.
POULSBO, Kitsap County — Just hours into the experiment, the prognosis was grim for salmon that had been submerged in rain runoff collected from one of Seattle’s busiest highways. One by one, the fish were removed from a tank filled with coffee-colored water and inspected: They were rigid. Their typically red gills were gray.
“He’s way dead,” David Baldwin, a research zoologist with the National Oceanic and Atmospheric Administration’s (NOAA) Northwest Fisheries Science Center, declared at the four-hour mark.
This was the fate of coho exposed to the everyday toxic brew of dirt, metals, oil and other gunk that washes off highway pavement after rains, directly into Puget Sound.
When that runoff was filtered through a simple mixture of gravel, sand and compost, however, the outlook was much brighter. Salmon exposed to treated water were healthy and responsive, even after 24 hours.
The research being conducted by scientists with NOAA, Washington State University and the U.S. Fish and Wildlife Service offers a promising solution to stormwater pollution, a major problem for Puget Sound and other streams and lakes in the nation.
With pollution from industrial pipes closely regulated, cities and states are more often tackling stormwater runoff that results from everyday activities: oils from leaky cars, pesticides from lawns and other pollutants that wash off roads and sidewalks and into streams and lakes.
Across the country, there’s been an aggressive push for rain gardens and other green techniques that rely on vegetation, soil or natural elements to slow and filter stormwater.
“The results are pretty stark,” said Jenifer McIntyre, a researcher with WSU who is part of the salmon experiment. “So far, what we’re seeing is that, absolutely, things like rain gardens are going to be part of the solution.”
Washington state now requires municipalities to adopt such green techniques to get a stormwater permit under the Clean Water Act after a conservation group sued.
A campaign is trying to get 12,000 rain gardens in Puget Sound to help reduce water pollution. Portland, Philadelphia, Kansas City, Mo., and other cities have embraced similar green technologies.
“It’s really promising, showing that rain gardens and bio-filtration are removing the pollutants that are killing the salmon,” said Chris Wilke, with Puget Soundkeeper Alliance.
More than a decade ago, researchers began noticing adult coho dying before they could spawn in urban creeks in Seattle. Monitoring over eight years, they observed fish consistently dying at high rates in Longfellow Creek and other urban creeks compared with a stream that wasn’t in an urban area.
The salmon swam erratically near the water’s surface, appeared disoriented and displayed other neurological symptoms. Disease or typical water issues such as temperature or dissolved oxygen didn’t appear to be a problem. More....