What does polluted stormwater have to do with fish hearing? Until today, I’d say absolutely nothing. But in the last weeks, new science points to polluted stormwater runoff as the culprit for damaging the ability for salmon and other fish to hear.
My first thought was…what on earth! That’s too much.
Stormwater is rain and snow melt that runs off our impervious surfaces, such as rooftops, paved streets, highways, and parking lots. As it flows into storm drains it carries along pollution including metals, oil, fertilizers, pesticides, soil, small plastic trash, and dog poop. In most areas, stormwater isn’t treated, instead it is routed directly to the nearest stream, river, or lake. Metals, such as zinc, copper, lead, and arsenic, are highly toxic to fish and aquatic life. Did you know that copper is released from brake pads, and car tires contain up to 1% zinc? These activities provide a constant source of copper and zinc to the stormwater toxic cocktail. According to the WA Department of Ecology, the agency that’s tasked with protecting, preserving, and enhancing Washington's environment for current and future generations, stormwater runoff is the leading pollution threat to our urban waters, streambeds, banks, and habitats.
In the last few years we’ve learned that stormwater contains a mixture that is deadly to coho salmon. In 2011, Dr. Jenifer McIntyre, a WSU aquatic ecotoxicologist, conducted a series of studies and found that stormwater runoff was toxic enough to kill adult coho in urban Seattle watersheds. In fact, stormwater runoff killed adult coho in as little as 2½ hours. Then, she filtered the stormwater runoff through a simple, soil based mixture, and the fish lived.
A similar study was recently completed by Dr. Allison Coffin, an assistant professor of neuroscience at WSU Vancouver. Her experiments on larval zebrafish and coho salmon showed that stormwater can damage hair-like sensors that fish use to find food, avoid predators, and navigate current. In her own words, “We’re showing that even if the fish are surviving the stormwater exposure, they still might not be able to detect the world around them as well, which can make it harder for them to find food or more likely for them to get eaten.”
In this recent study, Allison Coffin exposed fish to stormwater collected from Washington State Route 520 near the Montlake Cut, on which about 70,000 vehicles a day travel. That’s a lot of pollution from tires, brakes and oil leaks. Allison found that some of the fish exposed to this toxic mixture developed significantly less fewer hair cells than fish that were not exposed to stormwater. Some of the stormwater runoff was outright lethal. Coho embryos exposed to stormwater during development also had fewer hair cells, though to a lesser degree.
Why is this relevant to our Spokane River? Our salmon are long gone, and our native red band trout close relative of salmon and extremely sensitive to pollution, are struggling in Spokane River. Why? Our river has been severely altered, fish habitat has been degraded, the river is polluted with metals and PCBs, there’s sediment pollution from soil erosion, and there’s been a loss of protective shoreline vegetation. Plus the load of copper, zinc and other metals come down the drain when it rains.
Most fish are extremely sensitive to tiny amounts of zinc and copper. In addition to brakes and tires, the sources of metals in stormwater pollution include oils and lubricants from motor vehicles, stormwater discharges from industries, raw material and products, and exposed galvanized metal surfaces on buildings, fences, and equipment. It comes from all of us, our businesses, our lifestyles, and the transportation choices we make.
If we don’t take actions to save our fish, who will? Please help us by: Check your car for leaks. Check often, and fix leaks. Switch to brakes that are copper free. They’re available! Remove impervious pavement and surfaces from your property, and replace with multi-layered native vegetation. Come out to work parties and help plant and maintain streamside vegetation. Become a river advocate! Contact us if you want more ideas.