By Riley Adams, Whitewater Project Manager, Calibre Engineering
Fish or Fun? Communities and organizations across the United States are prioritizing projects involving both.
More and more municipalities are becoming aware of the potential benefits of river-based recreation in their communities. At the same time, we are learning from past mistakes, with state agencies, non-profits, and other organizations actively working to remove outdated and unsafe dams that have hindered or impeded the seasonal migration of native fish and other aquatic species.
Regulative agencies sometimes see these projects as mutually exclusive and conflicting. In reality, whitewater projects and restoration projects are often the perfect complements, with minimal compromise and potentially considerable benefits.
Whitewater projects can bring significant indirect economic impacts to cities and towns through dollars spent at local businesses, provide healthy outdoor recreation and educational opportunities, and re-brand a town as an outdoor destination. All you need is some gradient. Here’s where defunct low-head dams come in.
Dams create a physical barrier to aquatic species’ upstream migration. They typically also inhibit watercraft navigation and pose a serious safety hazard to swimmers and river enthusiasts by creating large hydraulics capable of recirculating and drowning swimmers.
Recently, there has been a major push to remove old dams to reconnect rivers and restore fish passage and navigability. On the Penobscot River, my home river in Maine, there has been aggressive movement to restore the Atlantic Salmon run that has all but disappeared, believed to be largely due to loss of access to traditional spawning grounds (and overfishing). The Natural Resources Council of Maine has fully removed two historic dams along the River and created a fish bypass around a third, opening up more than 2,000 miles of habitat that had been shut off to sea-run fish for years. As a result of these efforts, the state has already seen increased numbers of several native species, including Shad, Sturgeon, and Atlantic Salmon.
While complete dam removal is often the best solution for restoring fish passage, it does not work in every location. Often, in urban settings, upstream properties and adjacent businesses require some control of water levels, and so an engineered solution to stabilize channel grade following dam removal is necessary.
These opportunities are ideal for a shared-use recreation project. A typical low-head dam can provide suitable drops for multiple quality whitewater features. With continually advancing computer modeling and design techniques, fish passage can be integrated into whitewater structures, or a separate bypass channel can be incorporated, depending on the design requirements for target species and project site constraints. This solution can create a win-win situation in which upstream and downstream reaches are reconnected, a potential safety hazard is removed, and the community is left with a gathering space for river-based recreation and spectating.
A great example of this balanced design approach is the Columbus Riverfront Project in Indiana, which is expected to start construction in early 2025. The City of Columbus wanted to leverage its underutilized riverfront and simultaneously remove a failing low-head dam. The Indiana Department of Natural Resources (IDNR) wanted to remove the dam and restore fish passage and navigability. Calibre’s Whitewater Engineering Team worked with the City on a split channel design, which includes a three-drop Recreation Channel across one-third of the existing river width and a low-gradient Riffle Channel over the remaining two-thirds, focused on fish passage and navigability for watercraft. 2D computer modeling was used to ensure depths and velocities along the Riffle Channel met design criteria provided by the project fisheries ecologist and low-flow discharge criteria dictated by IDNR. A post-construction fish passage study and monitoring program is planned to evaluate project success and, if necessary, any required adjustments.
Columbus is just one of many communities taking advantage of the economic and social benefits of whitewater parks as a part of environmental conservation projects like dam removals. These projects are an opportunity to restore habitat and connectivity while educating communities on their local river environment and providing a space for good, clean fun!
Want to learn more about engineering solutions that accommodate both fish and fun? Contact Calibre’s Whitewater Team at (720) 310-8688 or visit www.calibre-engineering.com.
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