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Studies and Monitoring

Rocky Mountain National Park

Rocky Mountain National Park (NP), Colorado, has its own unique environmental concerns based on its particular ecology. Studies at Rocky Mountain NP focus on: atmospheric deposition of nitrogen and sulfur, critical loads development and application, ozone injury to plants, and the biological effects of airborne contaminants. Click on the tabs below to review air quality studies and current air quality monitoring at Rocky Mountain NP, as well as to access air quality data.

  • Studies & Projects
  • Monitoring & Data
  • Key References

Ongoing research in Rocky Mountain NP, Colorado:

Nitrogen Impacts

Long-term research in Rocky Mountain NP has found that, over time, increasing amounts of atmospheric deposition of nitrogen has caused changes in the plant communities and chemistry of alpine lakes (Baron 2006), and in the chemistry of vegetation and soils in spruce forests (Rueth et al. 2002). Ongoing research indicates that nitrogen deposition is now also at a level known to affect alpine plant community composition in adjacent alpine communities (Bowman 2006). The earliest of these documented changes began in the 1950s, when nitrogen deposition from rain and snow was about 1.5 kilograms per hectare per year; the “critical load” according to scientists. Reducing nitrogen deposition to below the critical load is a park management goal, and is a goal for the Rocky Mountain NP Initiative to protect and restore natural resources at the park (Porter and Johnson 2007). Results from the related Rocky Mountain Nitrogen and Sulfur Study shed light on understanding the origins of emissions currently affecting ecosystems and visibility at Rocky Mountain NP, further exploring how emission controls or reduction strategies can help mitigate pollution effects. (Source: overview fact sheet [pdf, 214 KB]; NPS 2004 [pdf, 614 KB]). For example, state and federal agencies are working with agricultural producers to foster voluntary ammonia best management practices (pdf, 475 KB) because fertilized crops and livestock production contribute to the nitrogen impacts at Rocky Mountain NP.

Airborne Toxic Contaminants Impacts

Air currents transport contaminants such as pesticides, industrial pollutants, and heavy metals from their sources, and deposit these toxics in rain, snow, and dryfall in the park. Airborne contaminants in fish, vegetation, snow, and lake sediments were analyzed for the Western Airborne Contaminants Assessment Project. Different airborne contaminants including historic- and current-use pesticides, the flame retardant PBDE, and mercury were detected in the park. Ongoing research is examining whether such contaminants may be a contributing factor to reproduction disruption in some park fish.

Ground-Level Ozone Impacts

During the summer months, ground-level ozone sometimes reaches harmful levels for visitors to Rocky Mountain NP. On days when ozone levels are expected to be high, the park issues health alerts advising visitors to limit their activity (Health Advisories Issued for National Parks). In addition to affecting humans, ozone harms plants. Ongoing surveys at the park reveal ozone injury on sensitive plants (project summary [pdf, 98 KB]), suggesting the harm ozone induces upon plants as well.

Air quality monitoring information and data access:

Air Pollutant/Impact

Monitoring Program

Sites and Data Access

Nitrogen Wet deposition NADP/NTN
Dry deposition CASTNet
Toxics WACAP
Visibility IMPROVE

Abbreviations in the above table:

    CASTNet: EPA Clean Air Status and Trends Network
    GPMP: Gaseous Pollutant Monitoring Program
    IMPROVE: Interagency Monitoring of Protected Visual Environments
    NADP: National Atmospheric Deposition Program
    NPS: National Park Service
    NTN: National Trends Network
    VIEWS: Visibility Information Exchange Web System
    WACAP: Western Airborne Contaminants Assessment Project

For more information regarding monitoring and data assessments conducted by the National Park Service, link to the NPS Air Quality Monitoring Program or to the NPS Air Quality Monitoring History Database for a history of active and inactive monitoring sites at Rocky Mountain NP.

Key air quality related references from Rocky Mountain NP, Colorado:

Baron, J.S., Rueth, H.M., Wolfe, A.N., Nydick, K.R., Allstott, E.J., Minear, J.T., Moraska, B. 2000. Ecosystem responses to nitrogen deposition in the Colorado Front Range. Ecosystems 3: 352–368.

Baron, J.S. 2006. Hindcasting Nitrogen Deposition to Determine an Ecological Critical Load. Ecological Applications 16(2): 433–439.

Bowman, W.D., Gartner, J.R., Holland, K., Wiedermann, M. 2006. Nitrogen Critical Loads for Alpine Vegetation and Terrestrial Ecosystem Response: Are We There Yet? Ecological Applications 16(3):

[IMPROVE] Interagency Monitoring of Protected Visual Environments. 2010. Improve Summary Data. Available at

Landers, D.H., Simonich, S.M., Jaffe, D.A., Geiser L.H., Campbell, D.H., Schwindt, A.R., Schreck, C.B., Kent, M.L., Hafner, W.D., Taylor, H.E., Hageman, K.J., Usenko, S., Ackerman, L.K., Schrlau, J.E., Rose, N.L., Blett, T.F., and Erway, M.M. 2008. The Fate, Transport, and Ecological Impacts of Airborne Contaminants in Western National Parks (USA). EPA/600/R-07/138. U.S. Environmental Protection Agency, Office of Research and Development, NHEERL, Western Ecology Division, Corvallis, Oregon. Available at

Landers, D.H., Simonich, S.M., Jaffe, D.A., Geiser L.H., Campbell, D.H., Schwindt, A.R., Schreck, C.B., Kent, M.L., Hafner, W.D., Taylor, H.E., Hageman, K.J., Usenko, S., Ackerman, L.K., Schrlau, J.E., Rose, N.L., Blett, T.F., and Erway, M.M. 2010. The Western Airborne Contaminant Assessment Project (WACAP): An Interdisciplinary Evaluation of the Impacts of Airborne Contaminants in Western U.S. National Parks. Environmental Science and Technology. Vol 44: 855–859.

[NPS] National Park Service. 2004. Nitrogen Deposition: Issues and Effects in Rocky Mountain National Park. Technical Background Document. Available at
(pdf, 614 KB).

Porter, E. and Johnson, S. 2007. Translating science into policy: Using ecosystem thresholds to protect resources in Rocky Mountain National Park. Environmental Pollution 149: 268–280.

Rueth, H.M. and Baron, J.S. 2002. Differences in Englemann spruce forest biogeochemistry east and west of the Continental Divide in Colorado, USA. Ecosystems 5:45–57.

Wolfe, A.P., Baron, J. S., Cornett, J.S. 2001. Anthropogenic nitrogen deposition induces rapid ecological changes in alpine lakes of the Colorado Front Range (USA). Journal of Paleolimnology 25: 1–7.

Featured Content

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Pollutants including nitrogen, toxics, ozone, and fine particles affect resources such as lakes, soils, and scenic vistas. Find out how on our Rocky Mountain NP Air Pollution Impacts web page.

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Last Updated: January 03, 2017