Urban Runoff Negatively Impacts Stream Biodiversity

It’s not exactly news that urban detritus isn’t good for the environment, and a recent BuildingGreen.com newsbrief reviews another recent study demonstrating that urban runoff is bad for steam biodiversity.

Researchers at the National Oceanic and Atmosphere Administration Northwest Fisheries Science Center (phew) designed experiments to assess how polluted stormwater runoff impacted insect populations in a small creek near Seattle by using rain gutter-like test channels containing rocks from biologically active streams that had been populated with insects. Unfiltered urban stormwater that contained pollutants was run through some of the channels; filtered water was run through the others.

Scientists running the experiment observed that insect populations exposed to the urban stormwater were 26% lower and experienced reduced species diversity compared to the the insect populations exposed to the filtered water. These findings support growing evidence that stormwater runoff should, wherever possible, be kept on-site. In urban areas this problem is of particular urgency, as stormwater runoff in affected by pollutants, rate, and temperature increases — all of which impact biodiversity in surrounding water bodies. 

The biological health of urban areas is not a factor in most design or policy decisions, but the impact of these (non)decisions can be significant. With increasing recommendations to manage stormwater runoff on-site, we have to hold ecology and function side by side in our development plans.

There are green building and landscaping strategies to help mitigate stormwater runoff and filter and slow the water on-site. Where land is affordable and available, rain gardens can be very effective solutions. And in dense and heavily developed areas, where space is at a premium, green roofs and suspended pavement systems provide great ways to manage the rate, volume, and quality of stormwater runoff in a variety of site applications.

Image: ign11

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