Dillersville Swamp
Lancaster County, Pennsylvania

The Little Conestoga Watershed (LCW), covering 65.5 mi2 in Lancaster County, Pennsylvania, is a key part of the drainage basin of the Conestoga River, which in turn flows into the Susquehanna River. One of the largest and ecologically most important wetlands in Pennsylvania, the Dillersville Swamp, is located in the watershed.

The Dillersville Swamp is a well known and historic wetland complex in the city of Lancaster, Pennsylvania. Over the years, urban development has encroached on this drainage area reducing its source of water primarily to urban runoff. Bounded by roads and a shopping center, the quality of the wetland has deteriorated over the years and the lack of hydrology has aided in this. Alcoa, Inc. (Alcoa) retained Wetland Habitat Management WHM to evaluate this wetland, to compare it to a reference wetland, and to assist in its enhancement.

The nutrient and sediment content of the creek is generally lower than the other tributaries of the LCW, while the metal content of the sediment is much higher, reflecting the different land use patterns. A small weir in the lower part of the watershed has trapped a large wedge of sediment with elevated metals. This sediment will be washed downstream if the weir is removed as part of a restoration project, necessitating careful study before any action was taken. Despite the highly impacted watershed much of the creek bank is still wooded, leading to relatively low water temperatures. Overall, this highly impacted tributary of the LCW had the potential to be restored as an urban stream corridor.

WHM completed a review of previous efforts and a Wetland Evaluation Technique (WET 2.0) analysis. This evaluation recommended augmentation of hydrology to the Dillersville Swamp. WHM subsequently proposed that an existing Alcoa discharge of treated groundwater be relocated to the wetland from its previous downstream location. WHM designed this discharge, the associated piping and obtained all local and state permitting to allow this to occur. A plan to seasonally adjust the discharge flow to the wetland was also presented.

Another important aspect of WHM's work involved our discussions with various local groups and individuals which had a deep commitment to the well-being of the Dillersville Swamp. WHM successfully managed this project and oversaw its success in the field.

L.K. Metzger
Dam

Phoenix Resources
Landfill Expansion

Dayton Dam

Houtzdale
Municipal

Ruff Creek
Stream
Restoration

Orchard Club
Subdivision Site

Oley Mountain
Estates