Marsh Creek and Willoughby Run are the two principle streams that flow through the park. Both of these steams bisect agricultural areas and are therefore susceptible to degraded water quality. The water quality of Marsh Creek is monitored through the Adams County Watershed Alliance.
The Gettysburg Municipal Authority is located on Marsh Creek, just north of the park boundary. The system has seven wells and a surface water intake on Marsh Creek that serves a population of approximately 12,000 people. The drinking water system primarily serves customers in Gettysburg Borough and both Straban and Cumberland townships
Watershed Alliance of Adams County Conducts water quality monitoring on Marsh Creek