Canyonlands National Park Air Quality Information
Both local and distant air pollutant sources affect air quality in Canyonlands NP. Power plants in Emery, Uintah, and Carbon counties, Utah, and Mesa County, Colorado, are the largest nearby point sources of both sulfur dioxide and nitrogen oxides. Pollutants also travel greater distances to the park from both mobile and point sources throughout the southwest.
The air quality related values (AQRVs) of Canyonlands NP are those resources that are potentially sensitive to air pollution, and include vegetation, wildlife, water quality, soils, and visibility. At present, visibility has been identified as the most sensitive AQRV in the park; other AQRVs may also be very sensitive, but have not been sufficiently studied. Although visibility in the park is still superior to that in many parts of the country, visibility in the park is often impaired by light-scattering pollutants (haze).
As part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, visual air quality in Canyonlands NP has been monitored using an aerosol sampler (1988-present), a transmissometer (1986-present), and a 35mm camera (1982-1995).
The U.S. Environmental Protection Agency’s Regional Haze regulations require States to establish goals for each Class I air quality area to improve visibility on the haziest days and ensure no degradation occurs on the clearest days. An analysis of 1990-1999 data indicates that visibility in Canyonlands NP is improving on both the clearest and the haziest days. Other parks on the Colorado Plateau, including Mesa Verde NP, Bryce Canyon NP, Petrified Forest NP, and Grand Canyon NP show trends of degrading visibility on the haziest days during the 1990-1999 period.
Surface waters in Canyonlands NP are generally well-buffered and, therefore, not likely to be acidified by atmospheric deposition. Most soils are also likely to be well-buffered from acidification. However, there may be areas in the park where rock is resistant to weathering and soils and water (e.g., in potholes) may be sensitive to inputs of acidic deposition.
There is concern that soils and vegetation in the park may be sensitive to nutrient enrichment from nitrogen deposition. In some parts of the country, nitrogen deposition has altered soil nutrient cycling and vegetation species composition; native plants that have evolved under nitrogen-poor conditions have been replaced by invasive species better able to utilize nitrogen. Studies are underway in Canyonlands NP to investigate nitrogen effects on soil dynamics, exotic plant invasiveness, and biological soil crusts.
Estimates of total nitrogen and sulfur deposition can be made by adding wet and dry deposition. Wet deposition is monitored in Canyonlands NP (1997-present) as part of the National Atmospheric Deposition Program/National Trends Network (NADP/NTN). The site ID is UT09. Rates of atmospheric deposition of nitrogen and sulfur in rain are relatively low in Canyonlands NP, but elevated above natural conditions. The data record is insufficient for a detailed trends analysis. Other Colorado Plateau NADP monitoring sites show decreasing trends in wet sulfur deposition from 1990-1999; for wet nitrogen deposition, some sites show a decreasing trend, while others show an increasing trend.
Dry deposition rates are estimated for Canyonlands NP (site CAN407), 1995-present, as part of the Clean Air Status and Trends Networks (CASTNet). Data indicate that, for the period 1999-2001, dry deposition contributed about 60 percent of total inorganic nitrogen deposition and about 50 percent of total sulfur deposition. A CASTNet analysis of site data for 1995-2001 indicates that annual dry deposition rates of nitrogen have remained steady; dry deposition rates of sulfur have decreased slightly.
Several plant species that occur in Canyonlands NP are known to be sensitive to ozone (e.g., Amelanchier alnifolia, Pinus ponderosa, Populus tremuloides, Rhus trilobata). Tropospheric (ground-level) ozone concentrations have been monitored from 1992-present. An analysis of the data indicates that ozone concentrations have significantly increased in the park. The observed concentrations in Canyonlands NP fall within a range that may produce visible effects or growth effects on sensitive plant species under certain conditions. No symptoms of injury from air pollution have been reported for vegetation in the park; however, systematic surveys for ozone injury have not been conducted. A 1999 survey in Bryce Canyon NP, Cedar Breaks NM, and Zion NP found symptoms of ozone injury on vegetation at all three parks.
Additional information relative to air quality and air quality related values at Canyonlands NP is available in D. Binkley et al. 1997. Status of Air Quality and Related Values in Class I National Parks and Monuments of the Colorado Plateau. National Park Service. Denver, CO.