Jacob's Well, Texas - USA

Jacob's Well is a significant karstic spring, the largest perennial spring in the Texas Hill Country. It flows from the most extensive underwater cave in Texas, opening in the bed of Cypress Creek, a few miles north of Wimberley, Texas. The twelve foot (four meter) diameter mouth of the cave serves as a popular swimming and water recreation spot for the local land owners whose properties adjoin Cypress Creek. From the opening in the creek bed, Jacob's Well descends vertically for about thirty feet (ten meters), continuing from there at an angle as a series of chambers separated by narrow, often deeply silted and unstable necks, ultimately reaching a depth of at least one hundred-twenty feet (forty meters). From the dawn of recorded history until the modern era, the Trinity Aquifer-fed natural artesian spring gushed water from the mouth of the cave and as much as thirty feet (ten meters) into the air. Documented flow in 1924 was one hundred-seventy gallons per second (six hundred-forty liters per second), discharging six feet (two meters) into the air. This spring is the most visible source of Cypress Creek, and a source of water recharging the Edwards Aquifer.

Due to development in the area, the level of the Trinity Aquifer has dropped, affecting the flow of water through Jacob's Well. In the modern era, all that usually remains visible of the spring is a faint ripple on the surface of Cypress Creek. The spring ceased flowing for the first time in recorded history in 2000; it again ceased flowing in 2008. These events resulted in on-going measures to address local water conservation and quality. Hays County purchased fifty acres (202000 square meters) of land around Jacob's Well in 2010, to protect the spring from development. With an additional thirty-one acres transferred from the neighboring Jacob’s Well Natural Area (itself administered by the Wimberley Valley Watershed Association (WVWA)), the new, eighty-acre (323000 square meter) Westridge Tract will be administered by Hays County.
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