From the Associated Press via The Grand Junction Daily Sentinel:
The National Park Service says unsafe levels of a type of algae that can be harmful to humans have been found in the water of a central Colorado reservoir.
Park officials said they detected the presence of toxins that can be produced by algae blooms in water samples taken from Blue Mesa Reservoir.
The agency advised visitors to avoid contact with shallow waters in an area known as the Iola Basin and to avoid mats of algae throughout the reservoir.
The reservoir is part of Curecanti National Recreation Area west of Gunnison, Colorado.
Harmful blue-green algae is natural to the area but can spread quickly in warm, shallow water.