Grown women and men acting like beavers. There are some terrific outdoor tasks in the Park Authority when things have to get done.
East Barnyard Run is the stream that provides the lifeline of water to the Huntley Meadows wetland that is totally dependent on rainfall. The stream drains about one square mile of suburbia, an area that includes significant acreage of impervious surfaces such as streets and parking lots. So while bringing the wetland its liquid nourishment, the stream also delivers silt, nutrients and pollution that haven’t been filtered through nature’s normal processes. That creates a constant threat to the wetland ecosystem and all of the animals that call the wetland their home.
Park Authority staff has been doing a lot to protect the wetland from further damage. There’s been a stream restoration project along one tributary of East Barnyard Run, and there have been planting projects along the run’s two main tributaries over the past several years. The goal of these projects is to stabilize the stream banks to reduce erosion and the resulting silt deposits in the wetland.
This brings us to our crew of beavers. Their job was to help stabilize East Barnyard Run and reduce the silt and pollution flowing into the wetland. They created a natural material blockage, which is the fancy, formal way of saying they took what nature made and used it to slow the flow of the water. Asad Rouhi of the Northern Virginia Soil and Water Conservation District obtained a $3,000 U.S. Fish and Wildlife grant to build the blockages that would slow the water flow, reduce the amount of silt moving downstream, increase deposition upstream of the wetland and reduce erosion. Rouhi, Fairfax County Park Authority staff and park volunteers created four blockages using trees that had been toppled in recent storms. Large sections of tree trunks and large branches were systematically laid into the stream. Logs were then laid downstream of the blockage to protect the stream bed from erosion during storm events. A tractor helped move and lower the logs into the stream, however many of the heavy and cumbersome logs had to be moved by hand once they were in the stream. Cable and duck bill anchors driven into the stream banks and bed secured the blockages.
In order to determine the effectiveness of the blockages, longitudinal profiles of the stream in the vicinity around the blockages were recorded and cross sections of the stream were taken above and below each blockage. Data will be collected from these areas in coming years and compared to previous years.
Although the blockages seem like a great fix for any stream, Rouhi warns “these BMP’s (best management practices) do not apply to any location. The location needs to be selected carefully. We hope that long term monitoring of our project will help us come up with detailed information regarding the site selection, design specifications and intervals where these structures are located from each other.”
Huntley Meadows Park is an oasis in the middle of an urban and suburban conglomerate. The Fairfax County Park Authority owns and operates the Alexandria park, which has a wonderful mix of natural resource communities including forests, meadows and wetlands. The 40-acre central wetland is the largest freshwater wetland in the region and is the heart of the park. A 0.6 mile boardwalk traverses the wetland and allows people to get close to the wetland and its inhabitants, including dozens of species of birds, frogs, turtles, snakes and mammals.
Author Dave Lawlor is the resource manager at Huntley Meadows Park.
Learn about the upcoming wetland restoration project, a large-scale effort to improve biodiversity in the park’s central wetland, here.