Edwards Aquifer Authority Field Trip

April 28 • 8:30 a.m.-5 p.m.

This field trip offers you an introduction to the San Antonio Segment of the Balcones Fault Zone Edwards Aquifer — commonly known as the Edwards Aquifer — one of the most permeable and productive aquifers in the United States.

The San Antonio segment of the aquifer, which is the subject of this field trip, extends from the groundwater divide near Brackettville in Kinney County, east to the city of San Antonio in Bexar County, then northeast to the groundwater divide near Kyle in Hays County — a distance of approximately 180 miles. The aquifer is the primary source of water for approximately two million people in the region and provides most of the water for agriculture and industry. In addition, the aquifer discharges through a series of large springs that provide aquatic habitat for a number of threatened and endangered species, while springflow provides a significant portion of water for downstream interests in the Guadalupe River Basin.

This field trip will take you from the contributing (drainage) zone of the aquifer, across the recharge zone, and on to the artesian zone. Each of the stops has been selected to give you an insight into the complex geology, hydrology, and management issues of the aquifer and the region and include:

• Stone Oak Park, where we will look at the entrances to Bear Cave and Cub Cave and discuss urbanization of the recharge zone and contributing zones of the aquifer, aquifer dynamics, and karst hydrology.
• Drive-by of Genesis Cave, a 250-foot deep cave and recharge feature of the Edwards Aquifer, where you can see subtle karst features in the Edwards Limestone while we discuss stormwater retention features.
• Blanco Road and 1604, where we will discuss the results of the Panther Springs tracer tests, implications for the results for hazardous materials spills, groundwater monitoring program design in karst, and potential threats to the Edwards Aquifer.
• The 377 outcrop located in New Braunfels two miles west of I-35, where you’ll be able to view an outcrop of Edwards Limestone and discuss geology.
• Comal Springs/Landa Park in New Braunfels, where we will visit the large spring complex that makes up Comal Springs and discuss the junction of the recharge and artesian zones, spring hydrology, tracer testing results, and the Endangered Species Act. You will be able to view a large flowing artesian well in addition to the Comal Springs fault with 800 feet of displacement.
• Saline artesian wells, where we’ll discuss the saline water/freshwater interface, potential plans for utilizing saline water, deep aquifer biota (critters in the aquifer), and growth in the San Antonio area.

A box lunch and drinks will be provided.

You should plan to wear comfortable shoes (open-toe shoes are not recommended), a hat, and weather-dependent clothes. Please bring your camera and questions.