Fake beaver dams may be next big restoration tool for ecologists
Source: Lancaster Online
SELINSGROVE, Snyder County — Matt Wilson is a stream and restoration ecologist who dwells on the works of nature, then mimics them for healing streams.
So when he read about successful efforts in the Pacific Northwest to build artificial beaver dams to improve water quality in streams, he naturally jumped on the idea and determined to try it himself.
This I had to see.
So on a frosty early November morning, I made my way to the Susquehanna University campus. Inside the university’s Freshwater Research Institute that Wilson heads were more than a dozen students, alumni, local volunteers and anyone else Wilson could draft for the unusual experiment.
Matt Wilson, director of Susquehanna University’s Freshwater Research Institute, uses a power tool to pound stakes into a streambed in building an artificial beaver dam.
Wilson had found a forlorn stream on which to operate. Because of failing stormwater controls on upstream developments and a railroad, pulses of runoff during storms were cutting through the stream bottom, ever flushing sediment downstream into the Susquehanna and gouging it so deep that it no longer runs year-round.
“This is the most intensive erosion I’ve ever seen on the East Coast outside of a major city,” he noted. “There are trees that are just hanging out in space because they are undercut so fast.”
Wilson told the volunteers sipping coffee in front of him that he would be constructing eight simple artificial beaver dams, known among stream biologists as beaver dam analogs.
Stakes would be driven with power tools into the stream bed. Then branches from freshly cut Bradford pear trees — an unwanted invasive species found on campus — would be woven through the stakes to create a kind of strainer that would catch suspended sediment in the stormwater and allow cleansed water to pass on through.
The series of eight artificial beaver dams would be simple and inexpensive crude replicas of what beavers do when left to their own devices.
Unlike in other places where this has been tried, the immediate goal was not to attract wild beavers and let them take over with their vast engineering skills, though it is hoped that may happen in time.
Rather, in addition to trapping sediment, the artificial dams would blunt the corrosive force of erosion. Moreover, in time the built-up stream bed may carry water up and over the banks, creating shallow wetlands that can store floodwaters. That’s very likely how the stream functioned before man began manipulating it.
Scour chains placed in front of the dams will measure the dammed sediment and whether the stream bed is rising. With new pools of standing water, maybe the stream will reconnect with groundwater and become a year-round waterway again.
Volunteers were having fun erecting the simple buy foreign contraptions in the rocky stream bed. Students peeled away during the day to head to class.
Among those sending curious and hard-working help was the state Department of Environmental Protection, Pennsylvania Fish and Boat Commission, Trout Unlimited, Chesapeake Conservancy, and others. Continued
Source: Lancaster Online