LONGMONT, Colo. (AP) - State and federal agencies say harmful nitrogen pollution is still drifting onto fragile high-elevation ecosystems in Rocky Mountain National Park from Colorado highways, power plants and livestock operations.

A draft report released Wednesday said 2017 nitrogen pollution in the park was 38 percent higher than the target.

But the report recommends against activating a contingency plan to reduce pollution, saying nitrogen didn't increase much in the previous decade.

The report also says tougher state and federal rules for vehicle emissions and planned retirements of coal-fired power plants will lower nitrogen levels.

The Colorado health department, the U.S. Environmental Protection Agency and the National Park Service released the report.

Scientists say increased nitrogen worsens the risk of insect and disease outbreaks and makes it harder for ecosystems to respond to climate change.

SUGGESTED VIDEOS | Local stories from 9NEWS