Shallow depressions found in karst terrains may contain wetlands (karst pans) that fluctuate seasonally in response to climatic conditions. This study examined the ground-water hydrology of a chain of 17 wetlands, ranging in size from 0.06 to 0.4 hectares, located in an Appalachian karst valley in central Pennsylvania, USA. The study objective was to determine the contributing area of wetland source waters. A variety of hydraulic head, soil stratigraphy, and water chemistry data indicate that the combined contributing areas of these wetland ponds extend to a maximum distance of approximately 150 m from the ponds. The hydrologic catchment area of the ponds during January and February, 1999 (approximately 2–8 hectares) was significantly smaller than catchment area based on topography (69 hectares). The water source of the wetlands consists of direct precipitation inputs and shallow (0.5–6 m) perched ground water. The hydrologic catchment area of the ponds expands during wet periods and contracts during dry periods. The ponds have been shown to be perched above the regional water table.