Urban Runoff Bad for Biodiversity in Streams

Scientists have demonstrated that stormwater runoff has a negative impact on the biological diversity of urban streams. Researchers at the National Oceanic & Atmospheric Administration’s Northwest Fisheries Science Center ran experiments to measure the effects of polluted stormwater on the insect population of a creek in the Seattle area. The scientists created test channels (similar to rain gutters) and stocked them with rocks from healthy streams that were colonized with insects. Some channels received unfiltered stormwater (with pollutants), while the others received filtered water. At the end of the 2009 experiment, insect populations in the channels with unfiltered water had dropped by 26%, and species diversity had dwindled. These findings suggest that green building strategies that filter and reduce stormwater runoff, such as bioswales and green roofs, are important to the biological health of urban areas. For more information see www.nwfsc.noaa.gov.