The Kirkwood-Cohansey aquifer is an aquifer system in the New Jersey Pine Barrens. It covers approximately 3,000 square miles (7,800 km2) and receives about 44 inches of precipitation each year. About fifty percent of this water is transpired by vegetation or evaporates back into the atmosphere. A small amount enters streams and rivers as storm runoff. About 17 to 20 inches annually actually enters the ground. Some of this water that enters the ground is pulled down through the soil and reaches the water table.
General Characteristics
As its name implies, the Kirkwood-Cohansey aquifer consists of two geologic units. The Cohansey Formation, above, consists mostly of sand, while the Kirkwood Formation, below contains both silt and clay. This structure creates a water-confining layer below the aquifer while allowing the top layer of water-bearing sands to remain hydrologically connected to surface water. At 360 feet deep, the aquifer is prolific in wells and springs, with almost 1,000 high-capacity wells that yield on average 400 gallons per minute of groundwater.