The Genesee Tunnel is an underground water pipeline operated by the South Central Connecticut Regional Water Authority (formerly the New Haven Water Company), part of the Authority's source water distribution system. Its main inlet is housed in a small brick building on the shore of the west fork of the northern end of the Hammonasset Reservoir (41.3749°N 72.6187°W) on the Madison, Connecticut-Killingworth, Connecticut town line.