This talk is being given by Jenifer McIntyre from Washington State University. NOAA Fisheries and USFW have collaborated on this project.
Stormwater runoff carries chemical contaminants. What their impact on aquatic life?
Examples: Metals, oil and grease, plasticizers…
Coho salmon are like a stormwater sentinal- they spend the first part of their lives in freshwater. Also, there are very high rates of pre-spawner mortality in urban areas. For example you can find dead adult females full of eggs. They died before they spawned.
In a past study they raised fish from eggs in untreated stormwater, versus treated (filtered) stormwater. Eggs in the unfiltered water: High rates of death, low growth rates, cranial haemorrhaging.
In this study: Some invertebrates and zebrafish.
Six storm events. Exposure to stormwater runoff from a highway. Affects on zebrafish: death, small size, delay in hatching, swim bladder not inflating, small heart, deformed heart and jaw. Or a developing fish will not escape from the chorion. This was wh- en they brought water into the lab.
In 2012- Adult coho study- Expose adult coho to stormwater runoff. They exposed coho to clean well water. Another group exposed to stormwater runoff (including first seasonal flush events). Adult fish exposed to stormwater lost ability to stay upright and showed other sublethal symptoms after 3.5 hours exposure.
Now they are looking at treated stormwater. Exposing juvenile coho, mayfly nymphs, and mayflies. Treating the stormwater prevented and also completely eliminated symptoms that would have normally been seen with straight stormwater.
In conclusion, soil bioretention, in other words treating stormwater runoff, can greatly reduce the damage caused to aquatic life from stormwater.
In areas where urbanization is occurring, we need to make sure development occurs in a way that stormwater can be treated.
Audience Question: What do you do with the bioretention material (sand and compost) after it has been used to filter stormwater? McIntyre says: It will take many years to use up the capacity of these bioretention features. They are studying the design life of these features.
Road runoff can affect saltwater species in the same way. They have done studies in California on this.
This talk was very triking and disturbing, thought the potential to treat the stormwater looks promising.