and their relation to the dam removal process
W. Cody Fleece and Scott Peyton, Stantec Consulting Services, Cincinnati, Ohio
David Huntress, Stantec Consulting Services, Topsham, Maine;
Bryon Ringley and Travis White, Stantec Consulting Services, Columbus, Ohio;
Tim Taylor, Stantec Consulting Services, Charlotte, North Carolina;
James Kiser, Stantec Consulting Services, Louisville, Kentucky
Abstract:
The distribution and abundance of freshwater mussels in relation to low-head dam removal projects is an emerging topic that has been the subject of increased regulatory scrutiny in recent years. A common misperception is that low-head dams create homogenous, low-quality habitat throughout the length of influence. However, mussel density and community can be good and, in some cases, Federally listed species are known to occur in and around impoundments.
This study reviewed data produced from eight low-head dam removal projects in Ohio and Michigan. Catchments ranged in size from 862 to 4,170 square kilometers and dam heights ranged between 0.9 and 10.5 meters. Abiotic variables reviewed in this study included longitudinal and cross sectional patterns in sediment grain sizes, longitudinal patterns in depth and velocity, rate of pool drawdown, and suspended solids concentrations. Biotic response variables to these habitat conditions included mussel abundance, richness, diversity, and reproductive life history strategy. The distribution and abundance of special status taxa were also examined in relation to physical habitat conditions.
Based on these results, we propose a framework for six distinct habitat zones associated low-head with dams: 1) upstream free-flowing, 2) upstream transitional, 3) pool 4) pool scour, 5) downstream transitional and 6) free-flowing downstream. This framework is useful in various phases of the project life cycle. In pre-project planning phase, it can help to inform decisions regarding study designs for presence-absence surveys, methods of demolition, sediment storage and transport, fish host access, and water quality as they relate to potential impacts on species of high conservation value. In the implementation phase, this framework can be useful for identifying locations to focus mussel rescue and relocation efforts. Consequently, limited resources can be allocated and prioritized for habitats occupied by species of high conservation value rather than habitats suitable for short-lived, rapidly-colonizing, opportunistic species. For post-project monitoring, the framework provides a conceptual model for the nature of impairments caused by low-head dams and a science-based rationale for the expected response to dam demolition.
Biography:
Mr. Fleece is an aquatic ecologist specializing in the study of freshwater mussels and river restoration. His project work includes stream and lake habitat assessments, fish passage-barrier assessments, quantitative assessment of the relationship between stream flow and habitat suitability for aquatic species, habitat modeling, watershed planning, endangered species conservation, and fish and freshwater mussel surveys. Much of his recent work has focused on incorporating the physical tolerances and preferences of fish and freshwater mussels in stream restoration design, with particular emphasis on State and Federally listed species.
Mr. Fleece has consulted on projects in eighteen states and two Canadian provinces.