|Canyon Lake, Texas on a quieter day.|
One article on the accident reports that the water temperature of the lake was 55 degrees. According to United States Search and Rescue Task Force, most victims will be exhausted or unconscious in less than 2 hours in water of this temperature. Expected survival time is 1 - 6 hours. For victims not wearing life jackets, exhaustion would come more quickly and drowning would occur immediately after the victim becomes unconscious.
People often underestimate the danger of cold water, mistakenly thinking that swimming in 55 degree water might be the same as walking around in 55 degree air. However, as USSRTF points out, "Cold water robs the body's heat 32 times faster than cold air." So while an inactive person without extra clothing might start to shiver after an hour or more in 55 degree air, the same person will start to shiver within 2 minutes in 55 degree water.
What can kayakers learn from this tragedy? Wear your life jacket. Be aware of the danger of paddling in water below 60 degrees. Know your limits. Listen to weather forecasts before you go out. Be safe out there!