Friday, May 10, 2019

Antioch Cave Vault on Onion Creek Functioning Amidst Recent and Coming Rain

No Drought
Lovelady well height: 531 ft-msl (123 ft- Depth to Water)
Barton Springs: approximately: 100+ cfs 10-day average


Heavy rains late last week and throughout this week deposited a significant amount of water along the I-35 corridor, averaging 8.3 inches among Austin, San Marcos and Wimberley. These rains, and subsequent creekflow, have led to a significant pulse of recharge to the aquifers. District staff anticipated the surge and prepared Antioch by calibrating all instruments in use and shutting both intake valves before the storm arrived. Onion Creek at Buda reached a peak stage of 23.2 ft (8 ft above flood stage level) early Saturday (5/4) morning.

As seen on the graph below, Antioch’s automatic valve successfully opened at 10:30am Sunday (5/5) when flooding subsided and turbidity levels measured below 50 NTU. This allowed desired inflow where an acoustic doppler velocimeter took measurements of up to 10 ft/s inside the 36” intake pipe. This equates to 70 cfs or 31,400 gpm. On Monday 5/6, staff opened the manual valve to increase the amount of recharge into Antioch cave. Staff continue to monitor rain patterns and prepare Antioch for best management practice.


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