Lower Leon Creek stands out in regional toxic watershed survey 

Toxic Leon meets Wilson meets cell phone camera.

Greg Harman


A study of regional watersheds to be released later this year suggests the Lower Leon Creek, sandwiched between former Kelly Air Force Base on the east and Lackland Air Force Base on the west, deserves both its bad reputation and recently expanded fishing advisory.

While elevated levels of a variety of toxic chemicals were found across Bexar County's watersheds, it was only on the Lower Leon that researchers found the infamous herbicide and suspected human carcinogen DDT at levels known to damage biological systems. The findings were shared at a small meeting held last night at the Cuellar Community Center in Southeast San Antonio.

Many employees of the report's contributing agencies â?? San Antonio's Public Center for Environmental Health, San Antonio River Authority, and U.S. Geological Survey â?? attended. However, the count of concerned local citizens count could sadly be tallied by rubbing a few knuckles together. The poor turnout inspired even non-local presenter Jennifer Wilson, an Austin-based USGS hydrologist, who helped lead the study from 2007 to 2009, to open: “I thought we were going to have a little more of the community here.”

And, yet, thankfully, the nutshell is easily transportable: sickish water all over SA, but the sickest is still the Leon.

The team tested for a variety of pesticides, including DDT and its daughter products, banned coolant and transformer chemicals known as PCBs, hydrocarbons, and flame retardants.

In a 20-minute PowerPoint presentation, Wilson said that the PCBs showed up in half of all the samples, though not at levels expected to harm the biological environment. Organic chemicals such as pesticides were measured three times higher in the water itself during the “first flush” of a rainfall event than in streambed sediments analyzed. “There's a whole bunch of reasons that could occur, but that's not what this study's about,” Wilson said. However, she allowed in a follow-up question after the presentation, runoff from area fields, roadways, and businesses would impact to the water quality at such times.

The highest toxicities, those expected to cause damage to the aquatic environment, were found at Leon and Lackland near the old Kelly Golf Course and at Leon Creek and Quintana Road.

At Leon and Lackland, the team found DDT levels of 110 parts per billion, a level expected to cause adverse impacts on the aquatic species. Also the “daughter” products of DDT, or the chemicals DDT breaks down into, such as DDD and DDE at hazardous levels, 55 ppb and 41 ppb, respectively.

DDT has been banned since 1972 but it continues to persist in the environment. The herbicide was used extensively during the Vietnam War and was stored at Kelly AFB.

Downstream at Quintana Road, the Leon had harmful heavy metal contamination from cadmium at 6.5 parts per million and chromium at 150 ppm.

A range of chemicals were found in the San Antonio River beneath the point the Leon (and all the other studied streams) spilled into the river. At 410 and Elmendorf, a range of heavy metals and insecticides, including both DDE and DDD, were found at significant levels but below the point adverse impacts would be expected, Wilson said.

Streams and rivers sampled included the Medio, Elm, Medina, Lower Leon, San Antonio, Lower Salado, Calaveras, and Martinez. Both sediment and water column samples were taken.

The group's report is expected to be released later this year. A community fact sheet is also to be developed, Wilson said, and distributed in early 2011.



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