Evaluation of the Impacts of Highway Construction on Sediment and Benthic Macroinvertebrates in Appalachian Streams

Corridor H is a four-lane highway under construction in north eastern West Virginia. I used a variety of methods to assess the impacts of highway construction in the Lost River watershed, Hardy County, West Virginia. I designed a two part sediment sampler to be used to monitor sediment in paired sites upstream and downstream of highway construction. The two-part design, a base that remains embedded in the substrate, and a removeable trap, allowed for long-term placement of samplers without continual disturbance of the streambed. I used a laboratory flume to compare my sediment sampler design with other devices used to measure stream sedimentation. Based on the flume experiment, the efficacy of our sediment sampler was consistent with that of modified core samplers, and modified Whitlock-Vibert boxes. I monitored sedimentation using the in-stream sediment sampler at paired sites upstream and downstream of highway construction on two tributaries of the Lost River, Sauerkraut Run and an unnamed tributary. I also monitored changes in the benthic macroinvertebrate communities using an index of biotic integrity, the West Virginia Stream Condition Index. I found little difference in the amount of fine sediment collected at upstream and downstream sites during the three year study. The downstream site on Sauerkraut Run collected significantly greater amounts of sediment in 2003, prior to installation of sediment fencing. Benthic macroinvertebrate metrics did not differ significantly annually or seasonally between sites or between streams. In addition to monitoring sediment and the benthic macroinvertebrate community on Sauerkraut Run, I also documented changes in the stream channel in response to highway construction and high flow events. Alterations to the streambed during construction included placement and removal of a temporary culvert, straightening and regrading of a section of stream channel, and armorment of a bank with a gravel berm. I surveyed longitudinal profiles and cross sections in a reference reach and the altered reach of Sauerkraut Run from 2003 through 2007 to measure changes in the streambed. Changes to the streambed downstream of construction included channel widening and aggradation and then degradation of the streambed. The reference section remained relatively unchanged. I assessed the impacts of construction by monitoring benthic macroinvertebrate communities, and water quality, before, during, and after highway construction at paired upstream and downstream sites from 1997 through 2007. Highway construction impacts included an increase in stream sedimentation during the construction phase. This was indicated by an increase in turbidity and total suspended solids. Benthic macroinvertebrate metrics indicate a community more tolerant during, and after construction than in the period before construction. The percent of chironomidae and the Hilsenhoff Biotic Index increased, while percent of Ephemeroptera, Plectoptera, and Trichoptera (EPT) decreased. The variety of methods used in these five chapters allowed better understanding of how various impacts of highway construction, and environmental variables, such as high flows, interact to influence the biota and habitat of streams.