The Dripping Springs

Dripping Springs takes its name from a set of small seeps that settlers found here in the 1850s, on a tributary of Onion Creek a few hundred yards north of this road. They still run, and they are a good illustration of how Hill Country water works. That is Trinity Aquifer water, emerging where the ground has cut down to a permeable layer, and springs like it are what hold a base flow in Onion Creek through months when nothing at all is running off the surface. The creek itself begins in Blanco County near Johnson City and runs seventy-nine miles east to the Colorado River in southeast Austin. For most of its length it is a shallow, spring-fed creek working along the base of the Balcones Escarpment, and it is one of the most closely studied streams in Central Texas. Between here and the city the creek does two things that seem to contradict each other. It gives away a large share of its flow to the Edwards Aquifer through fractures in its own bed, and studies credit the upper reach with as much as forty percent of the recharge to the Barton Springs segment. It also produces some of the most dangerous floods in the region. In October 2013 a storm centred on its middle reach put water into hundreds of houses in southeast Austin, and the city has since bought and cleared much of that floodplain rather than rebuild it. Both behaviours come from the same rock. Limestone takes water quickly when there is a little of it, and sheds it just as quickly when there is a lot.