The East Kill's watershed, is mostly located within the town of Jewett, with a few small sections entering into the towns of Windham, Ashland, and Lexington. East Kill drains some of the highest slopes in the Catskills, including the Blackhead Mountains. The Blackhead Mountain range includes Thomas Cole Mountain, Black Dome, and Blackhead Mountain, the fourth-, third-, and fifth-highest peaks in the Catskills, respectively. The highest point in the East Kill watershed is at the summit of Black Dome Mountain in southeast Jewett. The average elevation of the watershed is approximately .