Scientist says toxic blue-green algae likely caused by cold weather Scientist says toxic blue-green algae likely caused by cold weather Most of the algae present at Lake Travis is harmless, but the LCRA said this year tests showed toxic blue-green algae mixed in. LAKE TRAVIS, Texas - The Lower Colorado River Authority is continuing to test the water in the Highland Lakes after ten locations of Lake Travis tested positive for toxins from blue-green algae. Most of the algae present at Lake Travis is harmless, but the LCRA said this year tests showed toxic blue-green algae mixed in. "Until you've got the all-clear, I would kind of avoid it," said John Higley, CEO and principal scientist for Environmental Quality Operations, an Austin-based laboratory that aims to detect, monitor, and eradicate invasive species.