Elevated Levels of Mercury Found in Fish in Rocky Mountain National Park

Mercury has been discovered in fish in some of the most remote national park lakes and streams in the western United States and Alaska. Mercury levels in some fish exceeded U.S. Environmental Protection Agency health thresholds for potential impacts to fish, birds, and humans.

The information about mercury, and its appearance in protected areas considered to be relatively pristine and removed from environmental contaminants, is in a recently published scientific report from the U.S. Geological Survey and the National Park Service.

This study of mercury in fish is the first of its kind to incorporate information from remote places at 21 national parks in 10 western states, including Alaska. Western parks were selected for this study because of the significant role that atmospheric mercury deposition plays in remote places, and the lack of broad-scale assessments on mercury in fish in remote areas of the west.

Mercury concentrations in fish sampled from these parks were generally low, but were elevated in some instances. The study examines total mercury in fish, of which 95 percent is in the form of methylmercury, the most dangerous form to human and wildlife health.

Mercury is harmful to human and wildlife health, and is among the most widespread contaminants in the world. It is distributed at a global scale from natural sources, such as volcanic eruptions (responsible for approximately half of atmospheric mercury emissions), emissions from the ocean, and forest fires, and from human sources such as burning fossil fuels in power plants, gold mining, and incineration of municipal and medical waste. Mercury is also distributed at local or regional scales as a result of current and historic mining activities. These human activities have increased levels of atmospheric mercury at least three fold during the past 150 years.

Between 2008 and 2012, NPS resource managers collected more than 1,400 fish from 86 lakes and rivers, and USGS scientists measured mercury concentrations in fish muscle tissue. The authors found that mercury levels varied greatly, both between parks and among sites within each park. In most parks, mercury concentrations in fish were moderate to low. In fact, mercury concentrations were below EPA’s fish tissue criterion for safe human consumption in 96 percent of the sport fish sampled.

However, the average concentration of mercury in sport fish from two sites in Wrangell-St. Elias and Lake Clark (Alaska) national parks exceeded EPA’s human health criterion. Additionally, mercury levels in individual sport fish at some sites from Lassen Volcanic (California), Mount Rainer (Washington), Rocky Mountain (Colorado), Yellowstone (Wyoming), and Yosemite (California) national parks also exceeded the human health criterion.

The National Park Service is currently coordinating with state officials regarding potential fish consumption advisories. Exposure to high levels of mercury in humans may cause damage to the brain, kidneys, and the developing fetus. Pregnant women and young children are particularly sensitive to the effects of mercury.

Mercury at elevated levels can also impact wildlife resulting in reduced foraging efficiency, survival, and reproductive success. Mercury concentrations exceeded the most conservative fish toxicity benchmark at 15 percent of all sites, and the most sensitive health benchmark for fish-eating birds at 52 percent of all sites.

For more information and to view the report, please click here.



Jeff
Rocky Mountain Hiking Trails

Antero Reservoir to be drained for drought management

Denver Water, in coordination with Colorado Parks and Wildlife, will close Antero Reservoir on May 1st to drain the reservoir to save water supply during the ongoing drought.

Antero Reservoir has the highest evaporation rate of any of Denver Water’s reservoirs, so draining and storing the water in Cheesman and Eleven Mile reservoirs will reduce system evaporation losses by about 4,000 acre-feet.

“We’re exploring as many ways as possible to be efficient with our water supply,” said Dave Bennett, water resource manager for Denver Water. “Antero is a drought reservoir designed to provide water to our customers during a severe drought. Moving water from Antero to Cheesman will allow us to make the water available for our customers and reduce evaporation losses to our system.

Denver Water is working closely with Colorado Parks and Wildlife to minimize the loss of fish during the drain and to allow the public to use the reservoir before it closes.

- Beginning Wednesday, March 20, the bag and possession limit on trout at Antero will be increased from two to eight fish with no minimum size restriction. All other fishing regulations apply.

- Immediately after the ice has melted off the reservoir, CPW staff will trap and relocate spawning trout. Once the fish have moved off the shoreline and inlet areas, the draining of the reservoir will increase significantly. CPW staff will install a series of screens below the reservoir to capture fish as they leave the reservoir.

- In March, the standard recreation regulations apply.
> South: Open 24 hours a day and camping is permitted.
> North: Open from a half-hour before sunrise to a half-hour after sunset.

- Beginning in April, Antero Reservoir will be open for recreational use from a half-hour before sunrise to a half-hour after sunset. No camping will be permitted. After the ice has melted, only hand-launched vessels will be allowed. No trailered boats will be permitted. Recreation will cease May 1st.

Drought conditions will determine when the reservoir can be refilled. The reservoir was also taken out of service to assist with water management during the drought that began in 2002.

Wildlife concerns and questions regarding fishing at Antero can be directed to Colorado Parks and Wildlife at 303-291-7227. For questions regarding Antero operations, contact Denver Water at 303-628-6117.


Jeff
RockyMountainHikingTrails.com