Quarry Dam, on the West Branch Ausable River just outside Lake Placid, has been identified for removal this summer. The removal is being conducted by the Lake Champlain Chapter of Trout Unlimited, in collaboration with others.
The abandoned concrete and timber crib dam, three feet high and about 50 feet long, is creating undesirable impacts on the fish and aquatic life.
The presence of dams or impoundments in a stream or river is known to disrupt the natural structure and function of that waterbody, including changes in the physical, chemical, and biological parameters both upstream and downstream of the barrier. These effects are dependent on the size of the structure, as well as the environmental setting, with impacts ranging from changes in sediment transport and water temperature to barriers to movement for organisms.
Quarry Dam blocks fish passage and the river upstream of the dam is generally broad and shallow with a sandy substrate, characteristic of a filled impoundment – not ideal trout habitat. Restoration of these free-flowing habitats and fish populations often drive dam removals. It is assumed that the removal of Quarry Dam will provide several benefits, including improved fish passage, aquatic habitat, and flow and sediment transport.
Unfortunately, many stream restoration projects lack monitoring data to fully evaluate the success of the project on fish and other aquatic organisms. For example, a survey of over 200 river restoration projects in the US found less than half had identified success criteria related to ecological parameters, although many indicated their projects were successful. The lack of monitoring, especially for smaller dam removals, lessens the impact of the positive outcomes of stream restoration. And not all restoration efforts achieve positive outcomes; several efforts have reported no effect or in some cases a negative effect. Increased monitoring of projects will help better inform us about techniques that work or do not work to achieve the desired physical, chemical, and/or biological improvements.
The monitoring plan for the Quarry Dam removal is designed to assess physical, chemical, and biological parameters upstream and downstream of the dam, both prior to and following removal (ideally for several years). It is anticipated that conditions will be improved for fish passage, providing access to rearing and winter habitat; for flow and sediment transport; more suitable water temperatures during mid-summer; and improved habitat upstream of the dam.
It’s important to document any changes and develop a better understanding of the effects of habitat and population fragmentation, as well as restoration of riverine processes on aquatic organisms in the West Branch Ausable River. One of our key questions we hope to answer is does removal of Quarry Dam increase the availability and use of brook trout refuges during summer?
Monitoring of the Quarry Dam site – both upstream and downstream of the dam – was initiated in June with installation of temperature loggers at several sites. These will remain in the water and record water temperature every hour for the next few months. Last week, biological and habitat monitoring began with assistance from the State University of New York College of Environmental Science and Forestry (SUNY ESF) Ecology of Adirondack Fishes class, led by Stephanie Johnson; Nicole Pionteck, River Steward with the Ausable River Association; and Maureen Murphy. Sampling included fish and benthic invertebrate collection and measurement of habitat parameters such as wet width, bankfull width, depth, and velocity at transects upstream and downstream of the dam. These data will provide information on conditions prior to dam removal for comparison to similar sampling efforts following dam removal. Not only did we obtain critical data, but students were able to learn field techniques and participate in data collection efforts, as well as develop a better understanding of the collaboration that is necessary on these projects.
The importance of monitoring restoration efforts cannot be overstated. While funding is often cited as the reason for not conducting monitoring, the lack of monitoring weakens the credibility of efforts to achieve positive outcomes, and monitoring costs are typically a small fraction of an overall restoration budget. Without assessing the outcome of restoration projects, we don’t know if our limited funds are being spent on the most effective projects.
Removal of barriers, such as outdated dams, is critical for reconnection of flowing water and organisms; monitoring will help to determine the effectiveness of this reconnection. I appreciate the efforts of the Lake Champlain Chapter of Trout Unlimited for pursuing this dam removal, understanding the importance of monitoring, and providing funding for this project. Hopefully, this will be an example for future restoration projects.
Photos, from above: Monitoring team (photo courtesy of Rich Redman LCC Trout Unlimited); and Quarry Dam during spring high flows.