Air quality at Canyonlands National Park
Most visitors expect clean air and clear views in parks. Canyonlands National Park (NP), Utah, is a wilderness of countless canyons and fantastically formed buttes carved by the Colorado River and its tributaries. Upwind emissions from disturbed dry lands, oil and gas development, and regional wildfires, as well as urban and industrial sources all contribute to air pollution in the park. Airborne pollutants can harm the park’s natural and scenic resources such as soils, surface waters, vegetation, and visibility. The National Park Service works to address air pollution effects at Canyonlands NP, and in parks across the U.S., through science, policy and planning, and by doing our part.
Visitors come to Canyonlands NP, a high desert on the Colorado Plateau in Utah, to enjoy scenic views of spectacular canyons, mesas, needle-like spires, and deep river gorges. Park vistas are sometimes obscured by haze, reducing how well and how far people can see. Visibility reducing haze is caused by tiny particles in the air, and these particles can also affect human health. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to this haze. Organic compounds, soot, dust, and wood smoke reduce visibility as well.
Arid environments, including most of the Colorado Plateau region surrounding Canyonlands NP, often experience airborne dust due to long-term aridity, sparse plant cover, and sensitive soil surfaces (Neff et al. 2013). Soil disturbances and severe wind episodes can increase dust concentrations but vary greatly in both space and time (Flagg et al. 2014). The U.S. Geological Survey (USGS) is currently monitoring patterns of dust emissions within and outside the park to more thoroughly understand background emission levels, seasonal dynamics, and other factors that may influence timing and levels of dust in the air. USGS scientists are using field, laboratory, and statistical modeling methods to carry out this work. A related research project is measuring the effect of vehicle-use and surface conditions on unpaved roads on dust emissions in and around Canyonlands NP.
Significant improvements in park visibility have been documented since the early 1990’s. Overall, visibility in the park still needs some improvement to reach the Clean Air Act goal of no human caused impairment.
- Reduced visibility, at times, due to human-caused haze from dust and other fine particles of air pollution;
- Reduction of the average natural visual range from about 175 miles (without pollution) to about 130 miles because of airborne pollutants that impact the park’s viewshed;
- Reduction of the visual range to below 90 miles on high pollution days.
Visit the NPS air quality conditions and trends website for park-specific visibility information. Canyonlands NP has been monitoring visibility since 1989. View a live dust monitoring webcam and explore air monitoring »
Nitrogen and sulfur
Nitrogen and sulfur compounds deposited from the air may have harmful effects, including acidification, on soils, lakes, ponds, and streams. Given the abundance of base cations in underlying park soils and rocks, surface waters in Canyonlands NP are generally well-buffered from acidification. However, the park's small pothole aquatic systems may be sensitive to incoming acid inputs. Additionally, small streams with steep-sided canyon walls in the park have little ability to retain nutrients and water, offering the landscape little opportunity to buffer potentially acidic run-off (Sullivan et al. 2011c; Sullivan et al. 2011d). Some plants are sensitive to acidification, search for acid-sensitive plant species found at Canyonlands NP.
Excess nitrogen can also lead to nutrient enrichment, a process that changes nutrient cycling and alters plant communities. Ecosystem sensitivity to nutrient enrichment at Canyonlands NP relative to other national parks is very high (Sullivan et al. 2011a; Sullivan et al. 2011b). Healthy ecosystems can naturally buffer a certain amount of pollution, but as nitrogen and sulfur accumulate, a threshold is passed where the ecosystem is harmed. “Critical load” is a term used to describe the amount of pollution above which harmful changes in sensitive ecosystems occur (Porter 2005). Nitrogen deposition exceeds the critical load for one or more park ecosystems (NPS ARD 2018). Northern Arizona University and the U.S. Geological Survey are conducting research on nitrogen critical loads to identify current nitrogen deposition gradients and to examine the ecosystem consequences of nitrogen deposition to national parks in the Four Corners region, including Canyonlands NP.
Research conducted near Canyonlands NP found that experimental nitrogen additions resulted in unexpectedly large increases in the growth of invasive exotic Russian thistle, also known as tumbleweed (Schwinning et al. 2005). This finding is similar to results of research conducted in the Mojave Desert, where nitrogen deposition has been found to promote the spread of fast-growing exotic annual grasses such as red brome (Brooks 2003, Allen et al. 2009). Increased cover of exotic grasses can lead to increased fire risk (Rao et al. 2010).
Visit the NPS air quality conditions and trends website for park-specific nitrogen and sulfur deposition information. Canyonlands NP has been monitoring nitrogen and sulfur since 1997. Explore air monitoring »
At ground level, ozone is harmful to human health and the environment. Ground-level ozone does not come directly from smokestacks or vehicles, but instead is formed when other pollutants, mainly nitrogen oxides and volatile organic compounds, react in the presence of sunlight.
Over the course of a growing season, ozone can damage plant tissues making it harder for plants to produce and store food. It also weakens plants making them less resistant to disease and insect infestations. Some plants are more sensitive to ozone than others. A risk assessment that considered ozone exposure, soil moisture, and sensitive plant species concluded that plants in Canyonlands NP were at low risk of ozone injury (Kohut 2007; Kohut 2004). However, estimated ozone concentrations and cumulative doses at the park are high enough to damage the leaves of sensitive vegetation under certain conditions. Dry conditions in the park generally limit plant respiration and ozone uptake. But, in moist areas along streams and seeps, plants may be more vulnerable to ozone leaf damage (Kohut et al. 2012). Ozone sensitive plant species at the park include Salix gooddingii (Goodding’s willow) and Fraxinus anomala (Singleleaf ash). Search for more ozone-sensitive plant species found at Canyonlands NP.
Visit the NPS air quality conditions and trends website for park-specific ozone information. Canyonlands NP has been monitoring ozone since 1992. View live ozone and meteorology data and explore air monitoring »
Allen, E. B., L. E. Rao, R. J. Steers, A. Bytnerowicz, and M. E. Fenn. 2009. Impacts of atmospheric nitrogen deposition on vegetation and soils in Joshua Tree National Park. Pages 78–100 in R. H. Webb, L. F. Fenstermaker, J. S. Heaton, D. L. Hughson, E. V. McDonald, and D. M. Miller, editors. The Mojave Desert: ecosystem processes and sustainability. University of Nevada Press, Las Vegas, Nevada, USA.
Binkley et al. 1997. Status of Air Quality and Related Values in Class I National Parks and Monuments of the Colorado Plateau. Chapter 7. Canyonlands National Park. National Park Service, Air Resources Division, Denver, CO. Available at https://irma.nps.gov/DataStore/Reference/Profile/585485.
Brooks, M.L. 2003. Effects of increased soil nitrogen on the dominance of alien annual plants in the Mojave Desert. Journal of Applied Ecology. 40:344–353.
Eatough, D. J., M. Eatough, L. J. Lewis, E. A. Lewis, E. M. Tomlinson, J. L. Gordon, N. L. Eatough. 1996. Apportionment of sulfur oxides at Canyonlands during the winter of 1990. II. Fingerprints of emissions from point and regional sources impacting Canyonlands. Atmospheric Environment 30(2): 283–294.
Flagg, C. B., J. C. Neff, R. L. Reynolds, and J. Belnap. 2014. Spatial and temporal patterns of dust emissions (2004–2012) in semi-arid landscapes, southeastern Utah, USA. Aeolian Research 15:31-43.
Kohut, B. 2004. Assessing the Risk of Foliar Injury from Ozone on Vegetation in Parks in the Northern Colorado Plateau Network. Available at https://irma.nps.gov/DataStore/Reference/Profile/2181489.
Kohut R.J. 2007. Ozone Risk Assessment for Vital Signs Monitoring Networks, Appalachian National Scenic Trail, and Natchez Trace National Scenic Trail. NPS/NRPC/ARD/NRTR—2007/001. National Park Service. Fort Collins, Colorado. Available at https://www.nps.gov/articles/ozone-risk-assessment.htm
Kohut, B., C. Flanagan, E. Porter, J. Cheatham. 2012. Foliar Ozone Injury on Cutleaf Coneflower at Rocky Mountain National Park, Utah. Western North American Naturalist 72(1): 32–42.
Neff, J. C., R. L. Reynolds, S. M. Munson, D. Fernandez, and J. Belnap. 2013. The role of dust storms in total atmospheric particle concentrations at two sites in the western U.S. Journal of Geophysical Research: Atmospheres 118 (19): 11,201-211,212. http://dx.doi.org/10.1002/jgrd.50855
National Park Service [NPS], Air Resources Division. 2010. Air quality in national parks: 2009 annual performance and progress report. Natural Resource Report NPS/NRPC/ARD/NRR—2010/266. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/662783.
Pardo, L.H., M. J. Robin-Abbott, C. T. Driscoll, eds. 2011. Assessment of Nitrogen deposition effects and empirical critical loads of Nitrogen for ecoregions of the United States. Gen. Tech. Rep. NRS-80. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern ReseCANY Station. 291 p. Available at: http://nrs.fs.fed.us/pubs/38109.
Porter, E., Blett, T., Potter, D.U., Huber, C. 2005. Protecting resources on federal lands: Implications of critical loads for atmospheric deposition of nitrogen and sulfur. BioScience 55(7): 603–612. https://doi.org/10.1641/0006-3568(2005)055[0603:PROFLI]2.0.CO;2
Rao, L. E., E. B. Allen, and T. Meixner. 2010. Risk-based determination of critical nitrogen deposition loads for fire spread in southern California deserts. Ecological Applications 20:1320–1335.
Schwinning, S., B. I. Starr, N. J. Wojcik, M. E. Miller, J. E. Ehleringer, R. L. Sanford. 2005. Effects of nitrogen deposition on an arid grassland in the Colorado Plateau cold desert. Rangeland Ecology and Management. 58: 565–574.
Sullivan, T. J., McDonnell, T. C., McPherson, G. T., Mackey, S. D., Moore, D. 2011a. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/313. National Park Service, Denver, Colorado. Available at https://www.nps.gov/articles/nitrogen-risk-assessment.htm
Sullivan, T. J., McDonnell, T. C., McPherson, G. T., Mackey, S. D., Moore, D. 2011b. Evaluation of the sensitivity of inventory and monitoring national parks to nutrient enrichment effects from atmospheric nitrogen deposition: Northern Colorado Plateau Network (NCPN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/330. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2168722.
Sullivan, T. J., McPherson, G. T., McDonnell, T. C., Mackey, S. D., Moore, D. 2011c. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: main report. Natural Resource Report NPS/NRPC/ARD/NRR—2011/349. National Park Service, Denver, Colorado. Available at https://www.nps.gov/articles/acidification-risk-assessment.htm
Sullivan, T. J., McPherson, G. T., McDonnell, T. C., Mackey, S. D., Moore, D. 2011d. Evaluation of the sensitivity of inventory and monitoring national parks to acidification effects from atmospheric sulfur and nitrogen deposition: Northern Colorado Plateau Network (NCPN). Natural Resource Report NPS/NRPC/ARD/NRR—2011/366. National Park Service, Denver, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2170594.
Sullivan, T. J. and T.C. McDonnell. 2014. Mapping of nutrient-nitrogen critical loads for selected national parks in the intermountain west and great lakes regions. Natural Resource Technical Report NPS/ARD/NRTR—2014/895. National Park Service, Fort Collins, Colorado. Available at https://irma.nps.gov/DataStore/Reference/Profile/2214130.
Sullivan T.J. 2016. Air quality related values (AQRVs) in national parks: Effects from ozone; visibility reducing particles; and atmospheric deposition of acids, nutrients and toxics. Natural Resource Report. NPS/NRSS/ARD/NRR—2016/1196. National Park Service. Fort Collins, Colorado. Available at https://www.nps.gov/articles/aqrv-assessment.htm.