Dear Editor, In an otherwise excellent article on vanishing prairies [“Dreaming of Buffalo,” News, Dec. 23] you say, “the Edwards Aquifer, which feeds Barton Springs ... contributes about 1% of the city's drinking water.” Developers' allies propagated this erroneous claim many years ago. Unfortunately, this myth sometimes gets repeated as "fact." The Tom Green Water Treatment Plant on Town Lake actually supplies 15 to 20% of the city's drinking water. And for much of the year, Barton Springs' flow is the major contributor to Green's water intake. From mid-October to mid-March, essentially the only flow into Town Lake comes from Barton Creek (see www.lcra.org/water/river_report.html). In fact, Barton Creek, due to the Springs, right now is the largest measured tributary to the Colorado River below the Llano River (see http://waterdata.usgs.gov/tx/nwis/current?type=flow). Later on in the year, more water in Town Lake does come from the Highland Lakes. Even then, Green may draw more from the aquifer because the mouth of Barton Creek is very close by upriver. Also, water of different temperatures doesn't evenly mix – cold water sinks to the bottom of Town Lake on warm summer days. Colder aquifer water could disproportionately supply the Green intake 8 feet below the lake's surface. An implied subtext to this debate is an unstated idea that the aquifer is expendable. However, a growing city that faces periodic droughts shouldn't throw away any high-quality water resource. Some real estate interests want to replace the Green WTP with a new water plant on Lake Travis. Even though it could cost utility rate payers more to build a new water plant than to expand the old one, these interests covet the downtown land that Green sits on. Other developers would love to further undermine the case for protecting Barton Springs. These are the original sources for the 1% myth.
[Rachel Proctor May responds: According to the Austin Water Utility, the figure is roughly 1%.]