Death Valley, CA (NPS) - 11 burros were recently found dead near Owls Hole Spring in Death Valley National Park. The cause of death is under investigation, but the National Park Service suspects a harmful algae bloom was to blame.
The NPS warns that the water in Owls Hole Spring should be considered unsafe for humans or pets to drink or touch. In addition, people and pets should not handle any of the carcasses. Park rangers installed a warning sign.
Algae and cyanobacterial occur naturally in water and are more likely to grow into a harmful algae bloom when water is slow-moving, warm, and contains high levels of nitrogen and phosphorous, such as from fertilizer or sewage, according to the Centers for Disease Control.
All three of those conditions existed at Owls Hole Spring this summer where the water is stagnant. Death Valley experienced its hottest summer on record this year and feral burros defecated in and near the water.
So far only dead burros have been found, but officials say other animals were likely affected.