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Antioch Cave on Onion Creek The Onion Creek watershed has a total drainage area of approximately 165 square miles upstream of Buda. Within this area, a 9.6 mile segment of Onion Creek traverses the Recharge Zone of the Aquifer and drops 155 feet with an average slope of 16.2 feet per mile. The aquifer's recharge zone located within the Onion Creek watershed has a total area of about 26.2 square miles. The onion Creek watershed above the recharge zone commonly referred to as the contributing zone is 138.8 square miles in area. Antioch cave is located about 2 miles upstream from Buda on Onion Creek. In 1991, the District acquired 38 acres of property that included Antioch cave. This picture shows the cave before the structure was built. 
The District built a best management practice (BMP) encasing the cave in 1997 through a 319h grant funded by TNRCC, this structure controls both recharge and non-point source pollution (NPS). The quantity of recharge is controlled by a 36-inch butterfly valve, which can be opened pneumatically. Water quality is controlled by allowing the first flush of NPS to pass by the structure, normally this takes a few days, and then the valve is opened to begin recharging less turbid water. 
The District has enjoyed some tremendous rainfall events in the past several years; in October 1998, the structure was open for 6 months after the rain event; November 2001, the structure was open for several months and it continues to be open after the July 4th rains. |
