By Steve Young
Sparrow Pond is an artificial wetland and stormwater remediation complex along the Washington and Old Dominion (W&OD) Trail between Route 50 and Columbia Pike in Arlington. Built circa 2000-2001, the pond has been very successful in capturing sediment that otherwise would have flowed into Four Mile Run, then the Potomac River, and eventually Chesapeake Bay and the ocean. But this success has meant the pond has been filling up with sediment and self-destructing. By Summer 2019 the pond was almost dried up. While restoration of the pond is planned for 2021–2022, in the meantime, the pond looked to be pretty dysfunctional. Then the beavers appeared.
We can only guess how the beavers arrived in the pond: Maybe from downstream via the Potomac River or Four Mile Run; maybe from somewhere upstream, perhaps riding the wave of the great flood of July 8, 2019. In any event, they went to work doing what beavers do: building a dam and a lodge for living quarters. In the process, they gnawed down vegetation, both for food and for their engineering projects. Their work was clearly visible from the trail and the viewing platform on the north side of the pond.
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Beaver munching on vegetation. Photo courtesy of David Howell. -
Aftermath of beaver deconstruction. Photo courtesy of Steve Young.
Since late this past summer, the beavers’ impressive dam has raised the water level by perhaps 4 to 5 feet, so that Sparrow Pond is indeed a pond again! Especially over the winter holiday weeks, my wife and I took several walks to the viewing platform, looking over the scene and marveling how it has changed.
While it was not a conscious plan to draw other onlookers, we were amazed by how many people came by, saw that we were looking at something, and took an interest in what was going on. Some folks were aware that beavers were at work; more had no clue. As a master naturalist, I found myself with a number of “teachable moments” as I explained the presence of the beavers and their ecosystem engineering. No one ran away with eyes glazed over!
It brought home to me how we, as master naturalists, have various opportunities to do some low-key teaching about the nature that surrounds us when people show an interest. I encourage you to visit Sparrow Pond and hang out for a bit, and maybe have your own teachable moment. And you may have opportunities closer to home in parks, on trails, or even in your own backyard to engage in similar low-key interactions.
Addendum 5-6-20:
A reader expressed concern that Arlington County may euthanize the beavers because they are in a pond where they do not belong.
We raised this issue with Alonso Abugattas, the National Resources Manager for Arlington County Parks. He replied that the county hopes the beavers will move on from the pond when work on the planned restoration project for the pond begins. A beaver dam would cause damage to the restoration work as well as the trail there, and all things under it. So, beaver baffles will be installed to keep them from returning in the future. Mr. Abugattas added that it is illegal to trap or move the beavers because they would then become someone else’s problem.
Arlington set out out a memo that has resulted in lowering the water level with the purpose of evicting the beavers from their lodge – we’ve (the W&OD walkers) have observed the brown beavers leaving the pond so we will no longer see the Howell picture (above).