Groundwater discharge zones in West Neck Bay, Shelter Island were mapped using direct contact resistivity measurements and transient underflow measurements. The study found that conductivity values varied from 280 S/cm in freshwater zones to 12,800 S/cm in high salinity zones. The discharge zone extended 10-75 feet offshore, with seepage velocities ranging from 1.27 x 10 -3 cm/s to 3.94 x 10 -5 cm/s. The total daily discharge due to underflow in the north-east section of the bay was estimated to be 1.72 x 10 6 /day, comparable to the recharge in the area estimated at 1.50 x 10 6 /day.