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The burial of headwater streams in drainage pipes reduces in-stream nitrate retention: results from two US metropolitan areas
Citation:
Beaulieu, J., P. Mayer, S. Kaushall, M. Pennino, C. Arango, D. Balz, K. Fritz, AND B. Hill. The burial of headwater streams in drainage pipes reduces in-stream nitrate retention: results from two US metropolitan areas. Presented at Green Infrastructure (GI) seminar series, Cincinnati, OH, March 27, 2013.
Impact/Purpose:
To inform the public about green infrastructure and underground storm drains.
Description:
Urbanization causes stream degradation in various ways, but perhaps the most extreme example is the burial of streams in underground storm drains to facilitate above ground development or to promote the rapid conveyance of stormwater. Stream burial is extensive in urban basins (up to 90%) and may exacerbate water quality problems by inhibiting a stream’s natural capacity to remove nutrients from the water column. To investigate the degree to which burial inhibits in-stream nutrient removal, we measured nitrate uptake rates in buried and unburied, exposed streams in Cincinnati, Ohio and Baltimore, Maryland. We found that a combination of elevated water velocity and reduced biological activity in buried reaches inhibits nitrate retention. The average nitrate molecule is transported downstream 29 times further before being removed via biological activity in buried versus exposed streams. Our research indicates that stream daylighting is a green infrastructure approach that urban planners should consider when designing water quality management plans. Stream daylighting is the process whereby a previously buried stream is exposed and routed through a new stream channel. Previous studies have documented the economic benefits of stream daylighting on surrounding communities via enhanced visual attraction of an area, urban regeneration, and enhanced property values. Our study is the first to demonstrate the potential for positive effects on water quality of stream daylighting.