INFLUENCE OF POORLY FUNCTIONING CULVERTS ON STREAM HABITAT AND INVERTEBRATE COMMUNITIES
Goals of most culvert restoration projects are focused on aquatic organism passage (AOP) rather than ecological impacts within watersheds. Stream simulation design (SSD) is a geomorphic and ecologically-based restoration approach that mimics natural channel structure, while bankfull/backwater design (BBD) allows culverts to fill on their own. As part of a culvert restoration project, we examined habitat qualities (current velocity, water depth, silt depth, organic matter standing crops, and substrate type) and invertebrate communities above and below four poorly functioning culverts in the Nicolet National Forest, WI set to be restored using SSD or BBD. Pre-restoration analyses revealed slower current velocities, higher water and silt depths, higher total and fine organic matter standing crops, and lower proportions of hard substrate types upstream of the culvert compared to downstream reaches at all sites. Poor habitat quality above the culvert resulted in lower tax richness, abundance, and biomass of sensitive invertebrate taxa at sites above the culverts. Pre-restoration data demonstrated negative ecological consequences in addition to AOP concerns associated with substandard culverts. Future work will document effectiveness of culvert replacement using BBD/SSD on habitat quality and aquatic communities.
Sue Eggert (Primary Presenter/Author), USDA Forest Service, Northern Research Station, firstname.lastname@example.org;