After showing that bioretention filtration of stormwater could prevent pre-spawning mortality in coho salmon, researchers at WSC and the U.S. Fish & Wildlife Service teamed with the City of Bellevue to pilot test a retrofit concept for existing stormwater detention ponds. The idea was to inexpensively and passively provide additional treatment to stormwater in detention ponds before its release into surface waters. The bioretention urban retrofit (BUR) concept was to encourage stormwater entering a detention point to pass through rolls of organic matter and sand (BURitos). Influent and effluent waters were measured for various chemical contaminants and toxicity was tested using developing fish embryos. The pilot study showed improved removal of contaminants and reductions in toxicity.
