Nitrogen pollution in Rocky Mountain National Park is 15 to 20 times higher than background levels and is causing “unnatural effects,” park officials say.
Recently published scientific research suggests the park’s nitrogen levels are about twice its “critical load,” or the point at which ecosystem changes begin.
Scientific studies “provide a body of evidence that nitrogen deposition has resulted in significant harmful effects on park ecosystems on the east side of the Continental Divide,” said Park Superintendent Vaughn Baker.
Pollution controls may be needed to blunt the nitrogen’s impact, state and federal air quality experts said Thursday.
The agencies looking to stem the pollution include the state health department, the National Park Service, the federal Environmental Protection Agency and the U.S. Geological Survey.
“We’ll never get there if we don’t reverse the trend,” National Park Service representative Brian Mitchell said at a meeting of a state Air Quality Control Commission subcommittee. “We need to turn the ship around.”
Currently, about 2.75 pounds of nitrogen per year fall on the average acre on the park’s east side, according to Baker.
Research has shown that nitrogen starts affecting the ecosystem when it rises above 1.3 pounds an acre.
Throughout the West, nitrogen fallout from cars, trucks, smokestacks and agriculture is estimated to be at least 10 times as high as the amounts deposited in pre-industrial time.
While buildup of nitrogen – which acts as fertilizer – has not killed fish or trees, one noticeable effect lies above treeline, where nitrogen is growing more grasses and fewer wildflowers in the tundra.
“That’s probably the most tangible change,” Baron said. “But if you’re coming from Kansas, it still looks fabulous.”
Other observed changes noted in scientific studies include:
More nitrogen-tolerant algae growing in the lakes in the Loch Vale watershed on the park’s east side.
Spruce trees now contain excess nitrogen, putting the forest at greater risk for disease and making it more vulnerable to drought and insect infestation.
Armed with the new scientific work establishing nitrogen “critical load,” the panel is looking to reduce air pollution in the park, which is also plagued by haze and ozone.
The Colorado Department of Public Health and Environment has come up with several options – including tightening oil and gas industry emissions and requiring ammonia emission controls at municipal water treatment plants.
Another option includes limiting traffic in the park and possibly increasing the use of shuttle services.
“At this point it’s really just a laundry list of ideas,” said Mike Silverstein, a senior air manager at the state health department.
In the coming months, a committee of air-quality officials will discuss target levels for nitrogen within the park.
In December, the state air quality control commission will begin discussing the options identified by the subcommittee.
Nitrogen levels in park sediments are high enough to affect plant growth for 40 to 50 years, according to research by Jill Baron, a U.S. Geological Survey researcher.
Baron detected the changes in the volumes and types of algae in lakes east of the Continental Divide, which are closest to Front Range cities, as well as the nitrogen content of the soil and foliage.
Staff writer Kim McGuire can be reached at 303-820-1240 or kmcguire@denverpost.com.
Staff writer David Olinger can be reached at 303-820-1498 or dolinger@denverpost.com.
