AN ASSESSMENT OF THE IMPACT OF LAND USE ON LONG’S PARK CREEK IN THE LITTLE CONESTOGA WATERSHED, LANCASTER PA

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. Long’s Park Creek, part of the LCW, is a candidate for stream restoration sponsored by a recently formed grassroots watershed alliance. Land uses in this 2.05 mi2 highly impacted watershed are predominately industrial, commercial, and infrastructure with minor wetlands, woodland, and agriculture. Each of these land uses affects the health of the stream in different ways. The urban development in Long's Park watershed distinguishes it from other tributaries of the LCW, which flow mainly through suburban developments and agricultural lands. This study, part of a KECK Geology Consortium funded project, linked the nutrient content of the water, metals in the stream sediment and the morphology of the stream channel with the land use patterns in the watershed.

The channel is highly modified by channelization, hard engineering of the banks, and floodplain destruction. Channel cross-sections typically show deep U or V shaped profiles with no floodplain development. Runoff is discharged into the creek either directly from adjacent impervious surfaces such as parking lots and roofs, or through pipes draining similar areas away from the channel. One of the largest and ecologically most important wetlands in Pennsylvania, the Dillerville Swamp, is located in the watershed. Unfortunately industrial and commercial development has drastically reduced the areal extent and natural function of the wetland. 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 is 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 has the potential to be restored as an urban stream corridor.