25 million gallons a day, to avoid Stage Three rationing
Now that the hot dry weather appears to be here to stay, the San Antonio Water System is going to the bank. To the water bank.
1200 WOAI news reports SAWS has begun withdrawing water from the Twin Oaks Aquifer Storage Recovery Facility, commonly referred to as the Water Bank, a massive naturally occurring underground cavern which is located in the Carrizo Aquifer, between 450 and 900 feet below the surface southeast of San Antonio.
"Currently we are pulling from there at about 25 million gallons per day," SAWS' Anne Hayden told 1200 WOAI news.
The Twin Oaks facility was first opened in 2004, in an attempt to deal with water needs during hot, dry periods such as the one we appear to be entering now. The facility stores water during rainy periods, and can store up to 100,000 'acre feet' of water underground, the size of a medium sized lake.
An 'acre foot' is the amount of water needed to cover one acre at a depth of one foot. It is the measure used for large amounts of water, and amounts to about 325,000 gallons per acre foot.
That means there is plenty of water down there, enough to allow the city to remove 25 million gallons per day every day for about four years. Hayden says during the heavy rains we received in February and March the Twin Oaks facility quickly replenished all the water which had been removed from it last summer, with withdrawals averaged about 40 million gallons per day.
"You can't ski on it, you can't fish on it, but it is really an amazing, secure source of water, and it is also protected from evaporation," Hayden said.
The water bank allows SAWS to get around restrictions on withdrawals directly from the Edwards Aquifer which have been imposed by courts and the Legislature.
Hayden says the water bank was successfully used last summer to avoid falling into very strict Stage Three water restrictions, and she is confident that it can serve that purpose this summer as well.
She says the fall of the Aquifer, which was very sharp over the past three weeks, has leveled off due to withdrawals from the Twin Oaks facility, and also due to the fact that the growing season for many area corn farmers has ended.
"Corn growers especially have to irrigate quite a bit during the season, but they typically harvest right around the Fourth of July," she said.
Hayden says the existence of the water bank does not mean that residents can avoid personal conservation. She says cutting back lawn watering, car washing, and other types of uses can go a long ways toward making sure there is enough water to go around this summer.