You are here:
Encouraging stormwater management using a reverse auction: potential to restore stream ecosystems
Citation:
ROY, A., M. A. MORRISON, W. D. SHUSTER, H. W. THURSTON, H. CABEZAS, AND H. CABEZAS. Encouraging stormwater management using a reverse auction: potential to restore stream ecosystems. Presented at 16th National Nonpoint Source Monitoring Workshop, Columbus, OH, September 14 - 18, 2008.
Impact/Purpose:
To inform the public.
Description:
Stormwater runoff is the primary mechanism by which urbanizing landscapes disrupt natural, stream ecosystems. Source control management has been demonstrated as an effective and cost-efficient method for reducing stormwater runoff; however, sufficiently widespread implementation throughout watersheds is necessary to result in stream improvement. In a small, suburban watershed in Cincinnati (OH), we used a reverse auction as an incentive to encourage homeowners to accept stormwater best management practices (BMPs) on their property. Eligible homeowners could submit bids for the minimum compensation that they would require to accept a free rain garden and/or up to four rain barrels. Bids were subsequently ranked according to bid amount and potential environmental benefits (based on parcel-scale impervious surface area, soil infiltration capacity, and proximity to a stream), and awarded based on the most environmentally effective BMP at the lowest price. The first auction was held in spring 2007. Of the 350 homeowners, we received 73 bids (~21% response rate), including 57 bids for rain gardens and 62 bids for a total of 121 rain barrels. Approximately two-thirds of the bids were for $0, indicating that a majority of bidders did not require an additional incentive beyond BMPs installed at no charge. For the 50 rain gardens actually installed, we calculated a total watershed detention runoff volume of 128 m3 at an average cost of $362 per m3. For rain barrels, total detention volume was 26.4 m3 across 100 barrels, and the cost per volume of detention was $1043 per m3. Although BMPs did not disconnect an appreciable amount of effective impervious area from stream channels (0.2–0.4% across subwatersheds), we estimate that 16–28% of runoff from impervious surfaces in a relatively frequent size (0.6-cm or 0.25-inch) rainfall event was captured by BMPs in the various subwatersheds. A second auction in spring 2008 will determine whether repeated opportunities for BMP acceptance can result in additional and substantial increases in runoff detention throughout this watershed. To determine the effectiveness of BMPs at restoring stream ecosystems, we have established a before-after-control-impact monitoring program in two control, and four impacted (i.e., with BMPs) subwatersheds. Streams were monitored for hydrology (5-min), water quality (baseflow and stormflow), and biotic assemblages (periphyton and macroinvertebrates) for two to four years prior to BMP implementation. Ongoing monitoring of BMPs, stormwater outfalls, and subwatershed tributaries will ultimately determine the extent to which this approach is effective at restoring stream ecosystems.