The Well
Jacob’s Well is a perennial spring located in Hays County, Texas, near the towns of Dripping Springs and Wimberley. This site is a popular tourist attraction due to its striking scenic beauty...the clear, cold water that issues from the Trinity Aquifer and flows into Cypress Creek is a favorite summertime swimming hole for both local residents and area visitors. However, unknown to some, beyond the inviting, sunlit waters that countless people enjoy is an extensive underwater cave system.
This system is comprised of a principal conduit (A Tunnel) that generally trends in a northwesterly direction from the spring opening and extends approximately 4,500 feet from the surface. The A Tunnel segment consists of two deep sections separated by a shallower central portion. The deepest point (137 feet) in the entire system occurs in the first deep section. A second, smaller conduit (B Tunnel) branches from the main passage and trends in a northerly direction for approximately 1,500 feet while maintaining a fairly constant depth. These conduits are the result of dissolution and erosion of soft, porous limestone strata that include the Lower Glen Rose, Hensel, and Cow Creek formations. Deposits of clay, chert, and gravel are interspersed throughout the cave.
Temperature of the water in Jacob’s Well remains a near-constant 68°F and visibility is typically excellent. The spring provides habitat to numerous species of fish (principally sunfish and perch); turtles; aquatic insects; crustaceans; and, most notably, the cave-adapted Fern Bank salamander (Eurycea pterophilia). Discharge from the spring has historically been noted to be constant, and, at times, even prolific. In the past, visitors often reported observing a ‘dome’ of water up to several feet in height over the spring’s opening. However, due to drought conditions and widespread development, in recent years, Jacob’s Well has periodically ceased to flow. The US Geological Survey maintains a subsurface monitoring device at Jacob’s Well which transmits real-time measurement data for several parameters. This information is available to the public online (see EXTERNAL LINKS tab).
This system is comprised of a principal conduit (A Tunnel) that generally trends in a northwesterly direction from the spring opening and extends approximately 4,500 feet from the surface. The A Tunnel segment consists of two deep sections separated by a shallower central portion. The deepest point (137 feet) in the entire system occurs in the first deep section. A second, smaller conduit (B Tunnel) branches from the main passage and trends in a northerly direction for approximately 1,500 feet while maintaining a fairly constant depth. These conduits are the result of dissolution and erosion of soft, porous limestone strata that include the Lower Glen Rose, Hensel, and Cow Creek formations. Deposits of clay, chert, and gravel are interspersed throughout the cave.
Temperature of the water in Jacob’s Well remains a near-constant 68°F and visibility is typically excellent. The spring provides habitat to numerous species of fish (principally sunfish and perch); turtles; aquatic insects; crustaceans; and, most notably, the cave-adapted Fern Bank salamander (Eurycea pterophilia). Discharge from the spring has historically been noted to be constant, and, at times, even prolific. In the past, visitors often reported observing a ‘dome’ of water up to several feet in height over the spring’s opening. However, due to drought conditions and widespread development, in recent years, Jacob’s Well has periodically ceased to flow. The US Geological Survey maintains a subsurface monitoring device at Jacob’s Well which transmits real-time measurement data for several parameters. This information is available to the public online (see EXTERNAL LINKS tab).