Wetlands, Marshes and Swamps

Within Valley Forge NHP, vegetated wetlands are found primarily within low areas near the Schuylkill River (Figure 3-4). Many of these depressions, located on the north side of the river, are remnants of the impounding basins originally made to remove coal silt from the Schuylkill River. The wetlands described below were identified from a review of park literature (Newbold 1994) and GIS data, including the National Vegetation Classification inventory (Lundgren, et al. 2002), as well as field observation.

South Side

The largest wetland in Valley Forge is located within the floodplain on the south bank of the Schuylkill River, between the railroad tracks and the river. Roughly 4,500 feet long and 600 feet wide at its widest, this wetland is almost entirely forested. Species in this wetland include tulip tree3, spice bush, wild black cherry, slippery elm, lesser celandine, garlic mustard, and false nettle.

Just east of the large south side wetland described above is a small depressional wetland opposite the Port Kennedy Train Station. In the spring, dominant species include lesser celandine and garlic mustard. In the fall, the ground cover is stilt grass, nettles, and sedge.

South of the Maurice Stephens House is a small, spring-fed wetland characterized by Indian hemp, common milkweed, sedges, and watercress.

South of the General Varnum’s Quarters building lies a small, triangular, emergent wetland. Spring-fed, it is characterized by standing water throughout the year. Cattails, numerous sedges, and rushes are predominant wetland species.

A spring-fed woodland seep is located near the park boundary on Mount Misery upslope from Lord Stirling’s Quarters, and it drains into Stirling’s Run. Tulip poplar and various oak species are dominant in the tree canopy, while the shrub layer is absent. Skunk cabbage and jack-in-the-pulpit are abundant in the herbaceous layer. Ferns, a few sedges, and grasses are also present.

North Side

The largest wetland on the north side of the river is on Fatland Island, a former island once located within the Schuylkill River channel. This mixture of emergent and forested wetland is long and narrow, paralleling the river for a distance of approximately 4,800 feet with an average width of 200 feet. The floodplain forest is dominated by sycamore and white ash. Emergents include a variety of sedges, smartweed, garlic mustard, lesser celandine, false nettle, mannagrass, and spike rush. Shrub species documented for this wetland include box elder and hackberry.

A wooded slough is located approximately 100 feet southeast of the Pawlings Road parking area (northwest corner of the park). Newbold (1994) speculated that it was “caused by a back channel of the Schuylkill River which formed an island between itself and the river.” Silver maples, green ash, and sycamores are dominant tree species. Other characteristic species include box elder, spicebush, false nettle, and stilt grass. Garlic mustard and lesser celandine dominate in the spring, and stinging nettles, smartweeds, and sedges dominate in the fall.

Vernal Pools

Two impounding basins are located on the north bank of the Schuylkill River, southwest of the Walnut Hill barn. Both the upper and lower basins were constructed during the mid-1940s as part of the Schuylkill River Project, an effort to desilt the Schuylkill River. Water was pumped from the river and deposited into the lower basin, the silt settled out, and the relatively clean water was returned to the river. During the late 1980s, coal silt was removed from the lower basin and sold by the commonwealth, leaving a series of nine pits. Two depressions in the upper basin and the nine pits in the lower basin retain water and support wetland vegetation through the summer in non-drought years.

The two largest vernal pools are located immediately south of the Walnut Hill barn. Tree cover is limited and when these pools are full, the vegetation surrounding them includes clovers, grasses, and goldenrods. Typically, these pools are dry in fall and entirely disappear. In the spring, dominant species include a wide variety of sedges and rushes. In the fall, the ground cover is stilt grass, nettle, and a variety of sedges. Seeds from river birches found in the basins are collected by the American Forestry

Association and propagated for sale in their Famous & Historic Trees catalog (American Forests 1993; NPS 1992). The remaining vernal pools in the impounding basins are inhabited by ground clovers, chickweeds, and sneezeweed. A smaller vernal pool is located on the south side of the park within the Keene Quarry. Vegetation surrounding the pool includes clovers, grasses, and goldenrods.