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Connecticut River © Jerry Monkman

On its journey to Long Island Sound, the Connecticut River passes farms, forests, towns and industrial cities built with its power. It courses more than 410 miles, passing rapids where bald eagles swoop for fish and marshes where great egrets stalk rich fishing grounds. Colorful plants like cardinal flower and swamp rose-mallow spear up at streamside.

But the Connecticut River also has a history of intense human use. Its streamside forests were converted to farms and fragmented by the expansion of cities. Turn of the century mills harnessed its main stem and tributaries for power, disrupting natural flow. Pollution and changes to streamside lands took a toll on fish and other wildlife that is still felt today.

Where appropriate, dam removal can restore habitat, flush out pollution and enable fish to swim between river and sea. But removal is not always feasible; many larger dams in this watershed mitigate flood damage and provide energy and water for communities.

What if there was a way forward that could balance all of these essential needs? Working with the Army Corps of Engineers, The Nature Conservancy is developing a computer model that will help dam managers explore ways of releasing or storing water that are more compatible with a river’s natural processes.

Keeping the Symphony of Life in Tune

A river ecosystem is like a symphony orchestrated with rising and falling water levels, with plants and animals reacting to natural changes in flow. Rising water levels are a “cue” to many fish that it’s time to spawn. And many trees and wetland plants disperse their seeds to take advantage of moist floodplains along rivers that flood seasonally.

But these seasonal flows are suffering across all four states the river crosses. As Kim Lutz, director of the Conservancy’s Connecticut River program, explains, “To make a real difference, we know we have to work at the scale of the problem.”

As with all good science, the project began with a series of questions. “We wanted to find out how much water the Connecticut River and its tributaries need, and when they need it,” says Lutz. “Once we know how much change a river can withstand, we can help dam owners make better decisions about water use.”

Science for Sustainability

The model the Conservancy and the Army Corps of Engineers are developing will provide a sophisticated understanding of how water currently flows in the river and its tributaries, helping the Corps and other dam operators explore ways of releasing or storing water that are more in line with a river’s natural processes. It will also allow users to see the potential effect of climate change on the operation of these dams.

“Some may see this as an unlikely partnership,” adds Lutz. “But the potential results for communities and ecosystems are tremendous. We can’t restore these systems unless we open up the conversation about the services our rivers provide with more and more partners.“

To that end, the team’s basin-wide project is assessing opportunities to improve operations at approximately 70 large dams, and they will reach out to all large dam owners and operators to ensure their participation in the model’s development. The ultimate goal is to encourage decisions that achieve environmental benefits while maintaining important human uses. “The key,” says Lutz, “will be to work with nature’s water rhythms rather than against them.”

Story written by: Kate Frazer, The Nature Conservancy.