James Houle, Program Manager, University of New Hampshire Stormwater Center

Track: Policy

Abstract:

The Impervious Cover Model (ICM) was first proposed in 1994 by Tom Schueler and the Center for Watershed Protection.  It was first introduced as a management and planning tool to diagnose the severity of future stream problems in urban and urbanizing watersheds. Since its introduction the ICM has been adapted as a surrogate for impaired surface water attainment.  Numerous watershed studies throughout the country have correlated the percentage of impervious cover (IC) to the overall health of a watershed and its ability to meet designated uses.  National studies have also demonstrated that stream quality indicators will decrease as the percent of IC increases.  While there are strong correlations between pollutant loads and stormwater flows from impervious areas, the use of these models and other available planning and management tools are an emerging area of study. This presentation will cover recent advances in GIS applications of IC and land use data layers in relation to subsequent pollutant load modeling in urban watersheds.  Monitoring data from Berry Brook, a small 186-acre watershed in Dover, NH will also be presented.  Over the past five years the City of Dover has worked closely with the University of New Hampshire Stormwater Center (UNHSC) and the New Hampshire Department of Environmental Services to implement Low Impact Development stormwater management practices in order to improve runoff water quality before it reaches the brook.  These efforts have reduced the IC from 30% to 18% effective impervious cover (EIC).  Implementation and monitoring efforts continue and by the end of 2015 the watershed will have an EIC of 9.5%.