How Much Is Enough? Minimal Responses of Water Quality and Stream Biota to Partial Retrofit Stormwater Management in a Suburban Neighborhood

Abstract

Decentralized stormwater management approaches (e.g., biofiltration swales, pervious pavement, green roofs, rain gardens) that capture, detain, infiltrate, and filter runoff are now commonly used to minimize the impacts of stormwater runoff from impervious surfaces on aquatic ecosystems. However, there is little research on the effectiveness of retrofit, parcel-scale stormwater management practices for improving downstream aquatic ecosystem health. A reverse auction was used to encourage homeowners to mitigate stormwater on their property within the suburban, 1.8 km2 Shepherd Creek catchment in Cincinnati, Ohio (USA). In 2007–2008, 165 rain barrels and 81 rain gardens were installed on 30% of the properties in four experimental (treatment) subcatchments, and two additional subcatchments were maintained as controls. At the base of the subcatchments, we sampled monthly baseflow water quality, and seasonal (5×/year) physical habitat, periphyton assemblages, and macroinvertebrate assemblages in the streams for the three years before and after treatment implementation. Given the minor reductions in directly connected impervious area from the rain barrel installations (11.6% to 10.4% in the most impaired subcatchment) and high total impervious levels (13.1% to 19.9% in experimental subcatchments), we expected minor or no responses of water quality and biota to stormwater management. There were trends of increased conductivity, iron, and sulfate for control sites, but no such contemporaneous trends for experimental sites. The minor effects of treatment on streamflow volume and water quality did not translate into changes in biotic health, and the few periphyton and macroinvertebrate responses could be explained by factors not associated with the treatment (e.g., vegetation clearing, drought conditions). Improvement of overall stream health is unlikely without additional treatment of major impervious surfaces (including roads, apartment buildings, and parking lots). Further research is needed to define the minimum effect threshold and restoration trajectories for retrofitting catchments to improve the health of stream ecosystems.

Stormwater management network effectiveness and implications for urban watershed function: A critical review

“…In Figures , the brown line represents the expected trajectory of each metric if there are no SCMs installed and all run‐off is delivered to the stream untreated. On the basis of the studies described above (e.g., Bell et al, , ; Palla & Gnecco, ; Roy et al, ), treating a small portion of the impervious area often fails to produce detectible water quantity or quality changes for particular metrics. Purple lines in Figures represent the installation of SCMs in the watershed, with the length of the line representing the degree of SCM installation necessary to trigger a shift in the water quantity or quality response.…”

Hierarchical multi‐taxa models inform riparian vs. hydrologic restoration of urban streams in a permeable landscape

“…Furthermore, there are several other characteristics of riparian restoration that make it a beneficial restoration option. Roy et al (2014) found that 30% residential participation in a rain harvesting program in a suburban neighborhood in Cincinnati, Ohio, USA was not enough to improve local stream health and suggested that additional treatment of public roads, apartment buildings, and parking lots may be required, which would require additional participation by government and private industry. For example, current approaches to catchment-scale stormwater management, such as rain gardens, infiltration systems, permeable pavements, green roofs, and stormwater harvesting systems require public support and participation, which can be difficult to obtain (Roy et al 2008, Brown et al 2016.…”

More than money: how multiple factors influence householder participation in at-source stormwater management

“…The project offers an opportunity to evaluate methods for engaging the community in environmental protection and restoration actions, and to provide insight into public participation in decentralized stormwater initiatives for policy-makers and practitioners, gained through a combination of enquiry methods. By assessing influences on both participants and non-participants, we build on the biophysical and economic insights derived from the Shepherd Creek project in Cincinnati, Ohio, which also sought to restore a stream by installing stormwater control measures on private land (Mayer et al 2012;Roy et al 2014).…”