A single source is not yet determined, but car tires may be partially to blame.
A WSU researcher is studying how urban stormwater runoff affects fish health.
Jenifer McIntyre, assistant professor at the Washington Stormwater Center in Puyallup, Washington, is working with the National Oceanic and Atmospheric Administration Fisheries and the U.S. Fish and Wildlife Services.
Recent findings show specific fish species react differently to urban runoff, which is a problem for certain fish but not others. Researchers are trying to see how many coho and chum salmon survive to spawn.
Once coho salmon are exposed to urban runoff, they die in a few hours, but chum salmon do not get sick or die. Researchers are not sure why this discrepancy occurs.
“Coho are at risk where we build cities,” McIntyre said.
This is because coho live in lowland areas and do not spawn very far upstream, she said. There are high mortality rates for coho salmon due to urban stormwater runoff because they commonly spawn in creeks near cities.
If coho salmon are not surviving to spawn, there are fewer salmon eggs, McIntyre said. That means fewer salmon are born, which could affect the food chain. This includes the Puget Sound orcas, which commonly feed on coho.
So far, the research has been in the Puget Sound Basin, but researchers plan to do studies outside of the area because the problem has been happening north and south of the their study sites as well.
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