Scientists unveil new cave entrance

AUSTIN (KXAN) - It was a couple of decades ago, more or less. A couple of people were walking along the banks of a rushing Onion Creek near Buda in Hays County.

Cave enthusiast Bill Russell picks up the story:

"There was a whirlpool out in the creek and one of them walked up to see what it was, not realizing that a whirlpool under six feet of water has tremendous suction," said Russell. "He got close to it, just got sucked in and his body got jammed in the crack on top of this pit and he drowned."

It was several days before the water receded enabling authorities to remove the body. Shortly after that, area cavers started looking into the cause of the accident.

"We came in after the water flow had gone down some and went down in the crack," said Charlie Savves, an environmental consultant and area cave expert. "It was a real narrow crack with a waterfall in it and we had no idea what was down there. It was about a thirty-foot drop down to a roaring waterfall going down in there and a horizontal bedding plane going off."

A bedding plane, according to Joe Beery, a hydrogeologist with the Barton Springs/Edwards Aquifer Conservation District, is similar to what we see driving through cuts dug in hills for highway construction.

"When you look at the limestone or any of the outcrops of the road cuts, you notice these beds, well, that's what it is," said Beery. "A bedding plain is bed on top of bed, layers."

Some of the beds are more easily dissolved than others. Over time, they are eroded by water rushing through the cave, leaving narrow horizontal shafts between layers of solid rock.

It is those shafts that allow enormous amounts of water to be stored underground. The problem is that the same water that pours into a cave also carries all kinds of trash, rocks and other debris in with it, clogging up the cave channels and reducing flow to the bedding planes. The result: The cave becomes a stopped up drain, the water flow is interrupted and the aquifer loses much of its flow and volume.

In this case, the cave is Antioch Cave. It's mouth is situated right in the middle of a section of Onion Creek near Buda in Hays County. After more than a decade of work and some $800,000 in federal Clean Water Act grant money, the opening to Antioch is now protected by a huge concrete box. Sticking out of one end of the box is a long pipe, much of it constructed out of screening material.

"This screen was built to keep all the debris from going in the cave," said Dr. Brian Smith, the conservation district's Aquifer Science Team leader, standing on the pipe.

"In the last storm, we tested it; we had the valve open," Smith said. :"So we ended up with this acting like a big, giant Wet Vac. It sucked in every little leaf and twig and sediment and branch that was going by and was almost totally clogged up with that. So we realized how effective it is and how much water is actually going in there."

So the next time Onion Creek goes on a rampage, the pipes will automatically close to allow debris laden water to flow past the cave. Once the worst of the mess passes by, the valves will reopen, allowing copious amounts of water, filtered by the giant pipe screen to roar down into the cavern.

But there's another problem. That rushing water, itself, even without debris, can clog the flow.

"A lot of times, what will happen is as this huge velocity of water is coming down, it will lift up and turn a rock," said conservation district education leader Julie Jenkins. "And then right in behind that, little rocks will pile, and then pretty soon, what you have is you have this huge blockage."

So the next step for the district is to remove thousands of rocks by hand in an effort to open even more space underground. The result, in periods of drought, should be higher and cleaner flows of water through the city of Austin's popular Barton Springs pool seven days downstream from Antioch Cave.

The work should also benefit people living in rural areas who use well water drawn from the Aquifer. If more water reaches the bedding planes, it will take longer for the wells to go dry during severe droughts.

"So many of the people, whether they live on top of the aquifer or just in this area, it helps if they understand what the issues are: About how we need to conserve water, how we need to protect the aquifer and really protect the whole environment around us," said Smith. "Anything that's taking place on the surface affects what happens down here and on a good rainy day, we'll see a lot of water pouring in here and a lot of that water is filled with debris that's coming from upstream. There's chemicals in the water; there's bacteria and that gets in the aquifer and people are wanting to drink that and the salamanders want to live in that. So the more that people, you know, up there on the surface can understand what's going on down here, then the better they can help us protect this resource that's so important to all of us in the Austin area."