Rivers and Streams

The predominant water body in Valley Forge NHP is the Schuylkill River, the largest tributary to the Delaware River. Valley Creek, a tributary of the Schuylkill River, is a relatively narrow stream running north through the western portion of the park. Fourteen additional named streams also flow through the park and are described below. Other surface waters on the site include vernal pools and approximately 80 acres of wetlands.

Schuylkill River

The 130-mile-long Schuylkill River is Valley Forge’s most important water resource. It was the first river in Pennsylvania to be designated as a Pennsylvania Scenic River, and it also is the spine of a state and nationally designated heritage corridor. Approximately three miles of the river flow easterly through the center of Valley Forge NHP.

The entire Schuylkill River watershed covers approximately 1,916 square miles, most of which is located upstream of Valley Forge NHP. The park constitutes only 0.3% of the watershed. Land use patterns within the watershed vary among forested, agricultural, and urban, becoming increasingly urbanized from upstream to downstream. Within the park, the riverbanks are largely forested. These varying land covers benefit and impact water quality in different ways based on their pollutant loads, absorption ability, and runoff rates. A total of 34.32 miles of the Schuylkill have been defined as impaired by the DEP, including the three miles of river that flow through the park. The listing is due to PCB and chlordane contamination from outside the park.

Changes in the rate of stream flow are monitored by the U.S. Geological Survey (USGS). These rates are used in determining water supply issues and the health of the watershed. The USGS has 10 active monitoring stations along the Schuylkill. In Montgomery County, the river is measured at Pottstown. In 2000, the annual mean flow was 1,964 cubic feet per second or cfs. The maximum annual base flow recorded at this point occurred in 1952, when the flow was recorded at 3,050 cfs.

Valley Creek

Valley Creek, a perennial tributary to the Schuylkill River, is an essential natural resource within the park. Approximately 23-square-miles in size, the Valley Creek watershed holds the highest stream classification categories from both the DEP (Exceptional Value) and the Pennsylvania Fish & Boat Commission (Class A Trout Stream). About one square mile of the watershed lies within the park.

The Exceptional Value designation – Pennsylvania’s most protective stream designation – is based on water quality parameters including dissolved oxygen, pH, alkalinity, fecal coliforms, color, total dissolved solids, and temperature (Clough, Harbour and Associates LLP 2003). Designated in 1993, Valley Creek is the most urbanized watershed in Pennsylvania to have achieved the Exceptional Value classification (Cahill et. al. 1997). As a result of the designation, no additional development that would degrade the stream is permitted in the watershed. Conversely, the stream also is 303(d) listed by the commonwealth because of PCB contamination, turbidity, sedimentation, nutrients, and flow alteration.

The park lies at the bottom of the Valley Creek watershed. Only the last two miles of the creek flow through the park, and most of the watershed is located upstream of park boundaries, primarily in Chester County. While much of the watershed is undeveloped, agricultural practices, industrial discharges, and urban/residential stormwater runoff have impacted water quality in the stream. Inadequate stormwater management, water temperature management, and extremely high levels of flooding are the greatest threats to the Valley Creek watershed (Valley Creek Restoration Partnership 2004).

The population within the Valley Creek watershed more than doubled between 1980 and 1990, going from 15,600 people to 39,000 (NPS 1996). Increased development associated with population growth, including housing, industrial and commercial development, and roadway expansion increases impervious cover, pollutant loads, and surface water temperature. Impervious cover prevents precipitation from infiltrating the ground and also prevents pollutants from being buffered by natural ground cover. Influxes of runoff from impervious surfaces have been detected at temperatures as high as 140oF. During storms, precipitation rushes from impervious surfaces, accumulates pollutants, and washes them into the nearest river or stream. This occurs at a much higher rate of speed than it would in natural conditions, which causes increased rates of flow in the water body, increases streambed erosion, and inhibits the water’s natural pollution abatement abilities. The influx of warm waters into this coldwater limestone stream has severely detrimental effects on its biological components.

To monitor stream flow, the USGS installed a stream gauge in Valley Creek in 1983 near the park boundary, 100 feet upstream from the Pennsylvania Turnpike bridge.

Other Surface Waters

The four streams on the park’s north side are tributaries of the Schuylkill River. Two—Myers Run and Lamb Run—rise from beyond the park boundary and were 303(d) listed in 2004. Development upstream, lack of stormwater management, and poor erosion controls contribute to their 303(d) listing. These streams also are subject to severe flooding, resulting in streambank destabilization. In fall 2004, the volume and rate of stormwater during a hurricane destabilized masonry abutments in a railroad bridge that had stood in place for over a century, as well as gabions located at the confluence with the Schuylkill River.

Also on the north side, Walnut Hill Run and its tributary, Fawn Run, rise within the park boundary, but suffer from severe sedimentation, much of it due to recent construction of sewer and water lines along Pawlings Road. They flow into the Fatlands Island wetland, posing a risk of additional sedimentation to the wetland.

On the south side of the park, five streams flow down Mount Misery into Valley Creek. Stirling’s Run originates within a residential neighborhood and receives additional spring- fed water within the park. Covered Bridge Run is a highly modified intermittent stream that is severely impacted by stormwater runoff from the residential neighborhood. Fisher’s Run and Colonial Springs Run rise beyond the park boundary and are spring-fed streams with steep gradients. Two historic dams here are in danger of collapse, which would release dam debris and accumulated sediments into the stream. Lambert Run rises within the park boundary and is a steep, small stream that runs most of the year. All streams on Mount Misery are subjected to sedimentation due to the complete loss of ground cover from heavy browsing by white-tailed deer within the forest.

Only 100 feet of Wilson Run flows through the park before converging with Valley Creek, and it is severely affected by excessive stormwater runoff from upstream.

In the northwest corner of the park, Thropps Creek and Welsh Run flow into the Schuylkill. The banks of these creeks are highly eroded, and the bottoms are sedimented.

Trout Run, in the southeastern corner of the park, is rapidly deteriorating, and its banks are severely eroding, again due to the effects of poorly controlled stormwater runoff. Uncontrolled runoff from the PA Turnpike in particular has caused gullying within the park, as well as severe damage to the historic Ivy Hollow house, and contributes to flooding of the Glen Hardie neighborhood through which Trout Run flows.

Port Kennedy Run rises just north of PA Route 23 and flows into the Schuylkill. Several springs along its length contribute to its flow. The run is within the Asbestos Release Site and is severely impacted by asbestos wastes, as well as excess stormwater runoff from nearby roads within and beyond the park.