Sussex County and the Warren Conuty portion.of the Tocks Island Impact Area are primarily agricultural. Commercial, industrial and resort developments are occurring at an increasingly rapid rate. Ground water supplies approximately 60% of the estimated daily water consumption. Water utilities furnish the balance with surface water or a combination of ground water and surface water. Most of the ground water is obtained from rock wells; only a small percentage of the wells are located in unconsolidated Pleistocene deposits.Over 3,000 records of domestic, industrial and public supply wells were examined and are included in the report. The interpretations and conclusions presented are based on these driller's records which, although not precise or complete, give a good indication of reasonable expectations of depth and yield for each formation. There are no known areas where ground water levels have declined because of over pumping. Domestic supplies may be developed almost anywhere ir_ the study area. Moderate to large supplies can generally be developed from wells located in stratified drift, in cavernous members of the Kittatinny Formation and in shear zones near faults. Wells completed in the Precambrian crystallines, in the non-cavernous members of the Kittatinny Formation, and in the Martinsburg Formation usually will have very low yields: between 36to 47% will have yields of 5 gpm or less.The quality of ground water is generally good for most uses. Locally, the water will have to be treated for' hardness, low pH, high iron content and high SO 4.