This polyline shapefile consists of digital contours that represent the potentiometric-surface altitude of water in the Magothy and contiguous Jameco aquifer beneath Long Island, New York. The U.S. Geological Survey constructed a potentiometric-surface altitude map using ground-water levels measured in the Magothy and Jameco aquifers during the spring of 2013. Contours were constructed at a scale of 1:125,000 from water-level data collected at 101 groundwater monitoring wells. The potentiometric-surface altitude contours were digitized and compared to 1997, 2006, and 2010 potentiometric-surface altitude maps . The 10 foot contour interval ranges from 0 to 60 feet above the National Geodetic Vertical Datum of 1929 (NGVD29). This polyline shapefile is a digital representation of the potentiometric-surface contours presented in sheet 2 of Scientific Investigations Map 3326.