Foulkeways at Gwynedd, a local retirement community, contacted the Wissahickon Valley Watershed (WVWA) about improving a basin that had been taken over by phragmites and cattail. WVWA, working with Dr. Jeffrey Keller of Habitat by Design, developed a plan to address the plant invasion and improve the function of the basin. The phragmites and cattails were removed by excavating the root zone, thus eliminating the aggressive root systems and seed bed of those plants. A double forebay was installed to catch sediment, and a peninsula was added to increase the flow path. The basin was then planted with native shrubs and trees and a suite of herbaceous plant plugs and a seed mix to provide the diversity needed to attract the insects, birds, amphibians and reptiles that one would expect to see in a wetland habitat, using an Eagle Scout candidate and his troop as labor. The result is a functioning wetland with a beautiful array of wildflowers, grasses and aquatic plants that support a thriving animal community that is aesthetically pleasing for residents, has reduced water velocity, and improved the quality of water leaving the basin.
Monitoring is crucial, as the best designed and implemented designs still have to contend with natural forces that can disrupt the planned function of the basin. In spite of the removal of the entire root zone of the invasives, WVWA has had to return several times to remove cattails and phragmites that have tried to re-invade.
A contingency fund should be included in the planning. Due to a very wet winter, WVWA was unable to plant the plugs until June, resulting in a loss of many aquatic species. The following spring, WVWA was able to purchase more aquatic plant plugs and replant as necessary because such a possibility was planned into the project budget.
Using a seed mix as well as plugs increases the probability of success. If some of the plugs should fail, the seed mix will slowly make up for that. However, in a flood area such as this, the seed mix needs to be held down or it will float away with the first inundation. WVWA did this by spreading the seed and then covering with straw erosion control matting.
If possible, allow an extra year in your timeline estimate. Nature can intervene and cause delays that might put you past a grant deadline.
Watershed: Wissahickon Creek
Foulkeways at Gwynedd is located in Montgomery County in Gwynedd, PA, in the Wissahickon Creek Watershed.
Foulkeways at Gwynedd
Habitat by Design
Toth Brothers Excavating
Wissahickon Valley Watershed Association, Director of Stewardship