Researchers studying High Park Fire’s effect on mercury levels in Horsetooth Reservoir in Fort Collins

July 26, 2012

In the aftermath of the devastating High Park Fire west of Fort Collins, Colo., researchers are studying how fire transports mercury across the landscape and into the environment.

The two-year study began in June and will analyze mercury-level data from rainwater, air, water and fish samples from Horsetooth Reservoir in Fort Collins. Mercury accumulates in fish and other aquatic organisms, particularly those at the top of food chains in lakes, reservoirs and oceans, potentially becoming a health threat to humans.

“Mercury is accumulated in essentially all living things, and when these things are burned — fossil fuels and trees, for example — they emit mercury into the atmosphere which is then deposited on the landscape where it can be recycled by other living things,” said Jesse Lepak, aquatic research scientist with Colorado Parks and Wildlife. “It has been shown that forest fires can increase mercury deposition on the landscape, and further research is needed to understand the negative impacts of this increased mercury in the environment.”

The study initially evaluated mercury contamination in Colorado sportfish and researchers installed an automatic precipitation collector to measure mercury in rainfall just four days before the High Park Fire ignited.

“[Colorado State University] has collected detailed mercury data from Horsetooth Reservoir in the past, so we can now compare mercury levels in fish before, during and after the High Park Fire,” said Brian Wolff, a research associate working with CSU.

The study’s precipitation collector site, at CSU’s Foothills Campus, is part of the National Atmospheric Deposition Program’s Mercury Deposition Network, the first on the Colorado Front Range and one of about 100 sites that monitor mercury in precipitation throughout the U.S. and Canada. The network is donating a mercury collector that measures mercury in small particles in the air.

“These mercury collection devices will help fill a large void in mercury deposition data in the Mountain West region, and also provide invaluable information about the importance of forest fires for transporting mercury across the environment,” said Wolff.

Wolff hopes to have preliminary data in the coming weeks and will begin testing fish and other aquatic organisms in Horsetooth Reservoir next year to determine the fire’s effect on mercury bioaccumulation in the food chain.