Sequoia & Kings Canyon National Parks Air Quality Information
Overview
The San Joaquin Valley, one of the most polluted areas in California, lies upwind of Sequoia and Kings Canyon NPs. While there are relatively few major point sources in the San Joaquin Valley air basin, area and mobile source emissions are significant. Pesticide use in the San Joaquin Valley is also substantial, and pesticide transport downwind, into the parks, is of concern. Pollutants from as far away as the San Francisco Bay Area air basin are also transported to the parks.
Wet deposition has been measured in Sequoia NP at a National Atmospheric Deposition Program/National Trends Network (NADP/NTN) site since 1980 (site #CA75), as well as at a number of California Acid Deposition Monitoring Program sites. An analysis of the Sequoia NP NADP/NTN site data indicates wet sulfate concentration and deposition have remained relatively unchanged since the mid-1980's. During the same period, wet nitrate and ammonium concentrations and depositions have fluctuated significantly, but were relatively unchanged. Intensive research and monitoring in the Emerald Lake watershed in Sequoia NP shows that a substantial portion of the total annual deposition to the parks is released rapidly during spring when the accumulated snowpack melts. Therefore, nitrogen loading may be high during short time periods.
Dry deposition has been measured at Sequoia NP (site #SEK402) since 1997 as part of the Clean Air Status and Trends Network (CASTNet). Data indicate dry nitrogen and sulfur deposition are approximately equal to wet nitrogen and sulfur deposition. Data have not been collected long enough in the park to detect trends in dry deposition. Sequoia NP also had a dry deposition station as part of a National Oceanic and Atmospheric Administration (NOAA) network. The Sequoia NP site was at Wolverton (site #10) and ran from 1986 to 1998. The site helped describe total atmospheric deposition of nitrogen and sulfur for the Giant Forest area. However, the site likely underestimated deposition because its location did not provide direct exposure to the flow of pollutants from the San Joaquin Valley.
Sequoia and Kings Canyon NPs contain an exceptional array of pristine surface water resources, including scores of alpine and subalpine lakes, large river systems, and mountain streams. Alpine and subalpine lakes and streams in the parks are extremely dilute, and therefore, are very acid-sensitive. It is likely that many of the lakes and streams that exhibit lowest acid neutralizing capacity experience episodic acidification during snowmelt, particularly in response to nitrogen deposition. Even slight increases in nitrogen deposition could further threaten sensitive lakes and streams. Nitrogen deposition may also cause unwanted fertilization (eutrophication) in these dilute lakes.
Over the years, ozone has been monitored at five locations in Sequoia NP: at Ash Mountain from 1982 to 1996 (site #061070005), at Ash Mountain from 1999 to present (site #061070009), at Grant Grove from 1989 to 1995 (site #061070007), at Lookout Point from 1992 to 1994 and from 1997 to present (site #061070008), and at Lower Kaweah from 1984 to present (site #061070006). Ozone concentrations frequently exceeded the old human health-based 1-hr primary National Ambient Air Quality Standard (NAAQS), and they frequently exceed the new 8-hr primary NAAQS. California recently designated the park nonattainment for ozone. This indicates park visitors and employees are often exposed to unhealthy ozone levels. For all monitored years, and at all monitoring sites, seasonal ozone exposures have been well above ozone levels known to harm sensitive vegetation. Ozone concentrations increased significantly in the park from 1995-2004.
Based on many years of monitoring and research in the parks, severe ozone-induced foliar injury and growth effects are well documented on ponderosa pine (Pinus ponderosa) and Jeffrey pine (Pinus jeffreyi). In fact, foliar injury surveys conducted at 11 sites along the length of the Sierra Nevada Mountains in 1992 through 1994 documented the greatest amount of ozone-induced injury in Sequoia and Kings Canyon NPs. In plots in the Giant Forest area of the park, more than 90 percent of the surveyed Jeffrey pine trees were injured.
As part of the Interagency Monitoring of Protected Visual Environments (IMPROVE) network, visual air quality in Sequoia and Kings Canyon NPs has been monitored since March 1994 with an aerosol sampler. The U.S. Environmental Protection Agency’s new Regional Haze regulations require improving visibility in Class I air quality areas on both the best visibility and the worst visibility days. Visibility was relatively stable from 1995-2004.
Additional information relative to air quality and air quality related values at Sequoia and Kings Canyon NPs is available in T.J. Sullivan, D.L. Peterson, C.L. Blanchard, K. Savig, and D. Morse. 2001. Assessment of Air Quality and Air Pollutant Impacts in Class I National Parks of California. Technical Report NPS D-1454. National Park Service. Denver, CO.