And in some of these urban areas, up to ninety percent of the female were dying before they spawned, which is not a good thing for a population .Jew Anne Sprangburg, a toxicologist affiliated with the Northeast Fishery Science Centre.

  Researchers suspected that these deaths are partly a matter of bad timing. The fish often reaches the streams during the first showers of the rainy season, which flush chemicals from roads and parking lot into the water. Now Sprangburg and her colleagues have produced the first direct evidence that this runoff kills the salmon. Their study is in the journal of Pride Ecology. The researchers found that fish exposed to stormwater from Seatle highways quickly grew sick and died. Surprisingly though, the salmon didn't seem to  mind taking a dip in the cocktail of common road pollutants,inlcuding hydrocarbons and metals. That detail suggests that the current  ingredient in the runoff may be a different kind of chemical or lethal combination of several compounds.

  There is a lot of whole different matter that we haven't been able to measure or don't have the capability to measure at the moment.

  However, Scrangburg says there is a way to help the fish even before scientists hunt down the culprits. Her team also found that filtering runoff to just a few feet of soil makes stormwate safe for salmon. Cities can implement the simple form of clean water technology by building more systems, including roadside gardens to collect runoff from paved areas and pass it to soil before it enters urban waterways,literally a quick and dirty solution.