At Colorado’s largest reservoir, one national park scientist shifts her focus to toxic algae |

At Colorado’s largest reservoir, one national park scientist shifts her focus to toxic algae

Blue-green algae is native to Colorado’s largest reservoir. Two research projects seek reasons for its toxic bloom at Blue Mesa and how to stop it.

Stephanie Maltarich
The Colorado Sun
Blue-green algae, or cyanobacteria, is so thick in Blue Mesa Reservoir that it turns a motor boat's wake green as a research team motors across the lake on Aug. 16, 2022. U.S. Geological Survey Hydrologist Rachel Gidley, left, and Colorado Parks and Wildlife fisheries technician Mars Charlebois, right, are part of the research team monitoring the algae bloom in the reservoir.
Dean Krakel/Special to The Colorado Sun

GUNNISON — As Nicki Gibney steers her motorboat through the shallow waters of Blue Mesa Reservoir, she slows her boat to a stop. The deep blue water is thick with bright blue and green clumps floating on the surface. To the untrained eye, the bright colors and swirls look like a work of abstract art. 

“I tell the public to look out for what looks like pea soup or spilled paint,” Gibney says. 

Part of Gibney’s job is to help visitors understand that these curious clumps, cyanobacteria or blue-green algae blooms, may be toxic, and could cause serious harm to humans or animals who swim in the reservoir. If the toxins cross dangerous thresholds outlined by the Colorado Department of Public Health and Environment, the park posts “no-contact closures” that advise visitors against swimming or dipping along the shores of the reservoir. 

As Gibney expected, Curecanti National Recreation Area on Sept. 16 posted an alert: High levels of toxins linked to blue-green algae had been found in Blue Mesa Reservoir.  

For six years, Gibney has worked as an aquatic ecologist for Curecanti National Recreation Area and Black Canyon of the Gunnison National Park, and her job is to keep an eye on the water quality in both parks. Although water scientists have sampled the waters since 2001, Gibney’s work has changed dramatically in recent years. The ongoing megadrought in the West has changed the water in Blue Mesa Reservoir: the levels are low and the temperatures are warm — creating ripe conditions for harmful algae blooms. 


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