The south, east, and west sides of the Hanging Hills drain into the Quinnipiac River, thence into Long Island Sound; the north side into the Mattabesett River, to the Connecticut River, thence to Long Island Sound. Several notable reservoirs and natural bodies of water are located within the Hanging Hills or beneath its slopes, including Kenmere Reservoir, Hallmere Reservoir, Elmere Reservoir, Beaver Pond, Silver Lake, Mirror Lake, and Slopers Ponds. Merimere Reservoir, nestled between South Mountain and East Peak and punctuated by the rocky mass of Mine Island, is considered particularly scenic.