Springs: Dye Flows Downhill
When the Barton Springs/ Edwards Aquifer Conservation District announced the completion of its groundwater dye-tracing study last month, agency officials thought they'd at least get a couple of obligatory questions about the results. That didn't happen.
But had they issued a press release with a headline that screamed, "Shit flows downhill -- fast!" they likely would have piqued some interest. On the face of it, that's essentially what a team of scientists discovered when they injected nontoxic organic dyes into caves and sinkholes in the Barton Springs segment of the aquifer, as part of a far-reaching study conducted between 1996 and 2002.
The object was to determine not just the flow routes through the aquifer, but how quickly water flows through the underground channels leading to the primary point of discharge -- Barton Springs. "This study adds to our overall knowledge from both water quality and quantity perspectives," said Brian Smith, BSEACD program assessment manager. "We can now determine what kind of protective measures to put in place to keep contaminants out of the aquifer, and we know that we shouldn't be deceived by existing high-water levels, because water leaves the aquifer very quickly."
Researchers learned, for example, that dye injected into Dry Fork Sink on Kitcheon Branch -- a Williamson Creek tributary in Sunset Valley -- traveled the 41/2 miles to Barton Springs in less than 30 hours. Sunset Valley officials, mindful of the dangers facing the aquifer, have drastically changed their agenda in recent years -- from pro-growth (demonstrated by the string of big-box developments along Brodie Lane) to no-growth (evidenced by the city's ongoing legal entanglements with Lowe's).
Smith gently sidestepped the sticky subject of development over the aquifer, given the BSEACD board's no-growth reputation. But he did suggest greater care in planning for build-outs and roads over the aquifer's recharge and contributing zones. "We have to keep in mind that anything could happen -- a truck could wipe out carrying hazardous materials over the aquifer, and the contents of that spill could end up in Barton Springs in a matter of days, if not hours."