A North American Trail Ride Conference trail ride in Kansas scheduled for July 30-31 was canceled due to the presence of blue-green algae (BGA) in Big Hill Reservoir near Cherryvale. Ride organizers cited the health risks for horses and humans from BGA as the reason for the cancellation.

"We planned to use the many lake access points to cool the horses during a high temperature competition," said ride manager Priscilla Lindsey. "People were eager to compete, even with the heat, but we felt we had to put the welfare of both horses and riders first."

A photosynthetic bacterium called cyanobacterium that utilizes sunlight for energy, BGA grows rapidly on farm runoff nutrients such as nitrogen and phosphorus. Hot, dry conditions, stagnant water, and long summer daylight hours encourage the production of these harmful algal blooms.

Clinical signs of blue-green algae toxicity include photosensitivity, neurologic problems, bloody diarrhea, labored breathing, liver damage, and convulsions, although these signs might not be noticed before death occurs. Animals that survive might experience lasting problems including failure to thrive or photosensitization affecting white muzzle or other sensitive skin areas