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	I-93 Corridor Study in 2002

I-93 Corridor Study

by Laura Deming  Senior Wildlife Biologist

Audubon Society of New Hampshire conservation staff have recently completed a study to identify ecologically significant areas that may be impacted by the proposed expansion of Interstate 93 from Salem to Manchester. This study, which was funded by the U.S. Environmental Protection Agency (USEPA), brought together staff from the Audubon Society of New Hampshire (ASNH), the University of New Hampshire (UNH) Cooperative Extension, UNH Complex Systems Research Center (CSRC), and the Rockingham County Conservation District. The purpose of this group was to provide guidance to the New Hampshire Department of Transportation (NHDOT) during their mitigation process in an effort to accomplish meaningful conservation objectives with limited mitigation funds. Typically, mitigation for lands lost to highway construction occurs within a narrow corridor alongside the roadway and is therefore limited to protecting remnants of wetlands already impacted by the highway, or in some cases, the creation of wetlands in nearby upland sites. Mitigation sites tend to be relatively small, are often isolated from larger natural areas, and, because of their proximity to the highway, are dangerous places for wildlife species that must walk, slither, crawl, or hop across several lanes of traffic to reach them. Most mitigation "packages" address just the "direct" impacts of road construction (destruction of natural habitat within the actual construction zone). However, the proposed expansion of a major highway such as I-93 will undoubtedly result in "secondary" impacts-the increased population growth and development that will occur in the wake of the expansion. In recent years, major highway projects in four other states have provided mitigation funding to address these secondary impacts. The study group set out to identify important natural areas in a 23-town area that included the five "corridor" towns through which the highway runs (Salem, Windham, Derry, Londonderry, and Manchester), as well as surrounding towns that are expected to experience increased development because of the highway expansion: Concord, Bow, Hooksett, Allenstown, Pembroke, Dunbarton, Goffstown, Bedford, Candia, Deerfield, Raymond, Auburn, Chester, Sandown, Atkinson, Danville, Hampstead, and Pelham. By studying a larger landscape beyond the I-93 corridor, this group was able to identify several potential mitigation sites that were not only rich in ecological resources, but large and relatively well connected to existing conservation lands. The study committee identified ecologically significant areas using three sources of information: 1) georeferenced natural resource data for the region; 2) input from an advisory committee of natural resource professionals; and 3) local knowledge contributed by town residents in the study area. Georeferenced data were obtained from the state's Geographic Information System (GIS) database, also known as the Geographically Referenced Analysis and Information Transfer (GRANIT) system at the UNH Complex Systems Research Center. The study group looked at resource features that included aquifers, public water supplies, wellhead protection areas, wetlands, farmlands, unfragmented blocks (lands unfragmented by roads), and conservation lands. Additional data were obtained from the Reptile and Amphibian Reporting Program database at NHFG's Nongame Program Office and the New Hampshire Bird Records database at ASNH. These data were presented on a map that showed where resources overlapped. Places where several natural resources overlapped were identified as potential mitigation sites because of their high ecological value. A second set of potential mitigation sites was selected by a group of natural resource professionals familiar with the region. This group included staff from ASNH, the New Hampshire Department of Environmental Services, the U.S. Fish & Wildlife Service, the Nature Conservancy, the Society for the Protection of N.H. Forests, the N.H. Fish & Game Department (NHFG), Bear-Paw Regional Greenway Coalition, the N.H. Ecological Reserves Project (now the Living Legacy Project) and the N.H. Minimum Impact Development Project. The third set of potential mitigation sites was selected by residents of towns within the study area. Communities were invited to meetings to review the GIS maps of natural resources and to provide input on places in their towns that were important based on ecological, historic, recreational, and other values. Results of the natural resource mapping and mitigation site identification were presented to NHDOT. The maps illustrated dramatically the abundance of valuable natural resources in the towns beyond the highway corridor. In particular, the map showing unfragmented blocks of land greater than 500 acres revealed how much extensive, undeveloped natural landscape lies just beyond the I-93 corridor, in towns that will experience the impact of the highway expansion but may not receive any mitigation for those impacts. Currently, ASNH is working with staff from the Conservation Law Foundation, SPNHF, N.H. Public Interest Research Group, and the N.H. Sierra Club to raise awareness in study area towns of NHDOT's public hearing process, during which towns can provide input on the Draft Environmental Impact Statement. All comments must be received by December 13, 2002. For more information about the I-93 expansion project and the Draft Environmental Impact Statement, visit the NHDOT website: webster.state.nh.us/dot. This is your chance to provide commentary on the largest highway project in New Hampshire since interstates were built over 50 years ago.