For more information about National Park Service air resources, please visit https://www.nature.nps.gov/air/.
Air Pollution Impacts
Crater Lake National Park
Natural and scenic resources in Crater Lake National Park (NP) are susceptible to the harmful effects of air pollution. Nitrogen, toxic contaminants, ozone, and fine particles impact natural resources such as wildlife, surface waters, and vegetation, and scenic resources such as visibility. Click on the tabs below to learn more about air pollutants and their impacts on natural and scenic resources at Crater Lake NP.
- Nitrogen & Sulfur
- Toxics & Mercury
Nitrogen (N) and sulfur (S) compounds deposited from air pollution can harm surface waters, soils, and vegetation. Although Crater Lake itself is well-buffered and relatively insensitive to acidification, higher-elevation streams are less well-buffered and potentially sensitive to acidification from N and S deposition. In these headwater streams, changes in water chemistry from N and S deposition can harm fish, amphibians, and aquatic insects.
Crater Lake, however, may be sensitive to eutrophication (enrichment) from N deposition. Because the lake area represents a great majority of the watershed area, most N deposition falls directly on the lake and is not taken up by surrounding soils, trees, and plants, as is the case for many lakes in forested ecosystems. Atmospheric inputs constitute the major source of nutrients to Crater Lake, and the system may be very sensitive to even slight increases in N deposition. N enrichment can alter lake diversity and increase lake productivity, resulting in decreased lake transparency, an important resource value of the park. N deposition may also disrupt soil nutrient cycling and alter sensitive alpine plant communities by promoting the growth of weedier invasive species over native plants.
Higher elevation ecosystems in the park are more at risk to deposition than lower elevation areas because they receive greater amounts of snow and rain and therefore more N and S deposition. And, short growing seasons and shallow soils at higher elevations limit the capacity of soils and plants to buffer or absorb N and S.
Toxics, including heavy metals like mercury, accumulate in the tissue of organisms. When mercury converts to methylmercury in the environment and enters the food chain, effects can include reduced reproductive success, impaired growth and development, and decreased survival. Other toxic air contaminants of concern include pesticides, industrial by-products, and emerging chemicals such as flame retardants for fabrics. Some of these are known or suspected to cause cancer or other serious health effects in humans and wildlife.
Concentrations of toxic air contaminants including combustion by-products (PAHs), current-use pesticides (endosulfans, dacthal), and historic-use pesticides (HCB, a-HCH) are elevated in air and vegetation samples from Crater Lake NP (Landers et al. 2010; Landers et al. 2008).
Naturally-occurring ozone in the upper atmosphere absorbs the sun’s harmful ultraviolet rays and helps to protect all life on earth. However, in the lower atmosphere, ozone is an air pollutant, forming when nitrogen oxides from vehicles, power plants, and other sources combine with volatile organic compounds from gasoline, solvents, and vegetation in the presence of sunlight. In addition to causing respiratory problems in people, ozone can injure plants. Ozone enters leaves through pores (stomata), where it can kill plant tissues, causing visible injury, or reduce photosynthesis, growth, and reproduction.
There are a few ozone-sensitive plants in Crater Lake NP including Apocynum androsaemifolium (spreading dogbane), Pinus ponderosa (ponderosa pine), and Populus tremuloides (quaking aspen). A risk assessment that considered ozone exposure, soil moisture, and sensitive plant species concluded that plants in Crater Lake NP were at moderate risk of foliar ozone injury (Kohut 2004 [pdf, 120 KB]).
Search the list of ozone-sensitive plant species (pdf, 184 KB) found at each national park.
Many visitors come to Crater Lake NP to enjoy vistas of the vividly blue Crater Lake, the deepest lake in the United States. Unfortunately, this scene is sometimes obscured by haze, caused by fine particles in the air. Many of the same pollutants that ultimately fall out as nitrogen and sulfur deposition contribute to haze and visibility impairment. Additionally, organic compounds, soot, dust, and wood smoke reduce visibility.
Visibility effects at Crater Lake NP include:
- Reduced visibility, at times, due to human-caused haze and fine particles of air pollution;
- Reduction of the average natural visual range from about 160 miles (without the effects of pollution) to about 100 miles because of pollution at the park;
- Reduction of the visual range to below 50 miles on high pollution days.
(Source: IMPROVE 2010)
Explore scenic vistas through live webcams at Crater Lake National Park.
Studies and monitoring help the NPS understand the environmental impacts of air pollution. Access air quality data and see what is happening with Studies and Monitoring at Crater Lake NP.
Last Updated: December 30, 2016