Effectiveness of stream restoration following highway reconstruction projects on two freshwater streams in Kentucky

Abstract

After new highway construction near or across a stream, the site often requires remediation to reestablish suitable habitat for local biota. This study addresses effectiveness of environmental mitigation efforts for these construction projects, and contributes to the development of a protocol for environmental mitigation to be adopted by the Kentucky Transportation Cabinet. Effects of remediation on two small KY, USA, streams, Cedar Creek and Holts Creek, were assessed using U.S. EPA Rapid Bioassessment Protocols (RBP). Habitat assessments and fish species assemblage surveys (index of biotic integrity) were conducted for three sectors of each stream. A decrease in total habitat assessment scores was observed at the remediated sector in each stream. However, for both streams the IBI fish assemblage scores were similar for upstream and remediated sectors, indicating that habitat impact resulted in limited effects on fish assemblages. The overall score for the downstream reach of Cedar Creek also was similar to upstream and remediated sectors, but the downstream portion of Holts Creek scored lower, primarily because of reduced number of fish species and abundances. This was likely due to stream characteristics and lack of diversity. The U.S. EPA Rapid Bioassessment Protocols proved to be well suited for quantitative assessments of fish assemblages for small stream sectors with limited impacted areas. Although habitat quality scored somewhat lower in the remediated sectors of both streams, there were no major impairments of overall stream productivity and no apparent blockage of fish migration. The most apparent deficiencies in habitat restoration involved protective and riparian vegetation, resulting in diminished bank stability, increased prospects for bank erosion, moderate downstream siltation, and consequences of stream channelization.