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WACAP - Western Airborne Contaminants Assessment Project

A window into the contaminant situation at 20 national parks from the Arctic to the Mexican border.

WACAP Overview

The Western Airborne Contaminants Assessment Project (WACAP) was initiated to determine the risk to ecosystems and food webs in western national parks from the long-range transport of airborne contaminants. It was designed and implemented by the National Park Service's Air Resources Division in cooperation with many western national parks, the Environmental Protection Agency, the US Geological Survey, the US Forest Service, Oregon State University, and University of Washington.

The project objectives were:

  • Determine if contaminants are present in western national parks
  • If present, determine where contaminants are accumulating (geographically and by elevation)
  • If present, determine which contaminants pose a potential ecological threat
  • Determine which indicators appear to be the most useful to address contamination
  • Determine the sources for contaminants measured at the national park sites

Fact Sheets

A 4-page project summary and information transfer tool can be downloaded in a low resolution screen (letter, pdf 6 MB), high resolution screen (letter, pdf 49 MB) or high-resolution printer (tabloid, pdf 49 MB) version.


The WACAP report was published in Jan. 2008 and announced (pdf, 29 KB) in Feb. 2008. An errata sheet was posted in Nov. 2008, and the report PDFs posted have been updated accordingly. Access either the (A) entire Volume I – Final Report or entire Volume II – Appendices, or (B) individual chapters from either Volume I or II. report sections »

Scientific Publications

The WACAP study resulted in published journal articles by project PIs. Additionally, access WACAP abstracts from numerous oral and written presentations given by WACAP researchers and NPS staff at various scientific venues.

Popular Media

Feature stories highlight the WACAP study and design, results, and implications for a general, non-technical audience, while a WACAP interview and WACAP Video offer perspective from the public eye.


A MS Access database (zip, 12.8 MB) containing all the physical, chemical, and biological data collected as part of the WACAP study is now available. The database includes information on around 100 variables for over 2,000 samples. The user's guide (pdf, 337 KB) and metadata provide tips and detailed information for running the database.

Key Findings

Results from this project add to the body of science concerning contaminant transport and biological effects in remote national park ecosystems. A summary (pdf, 32 KB) of WACAP findings describes their impacts and resulting actions. more key findings »

Human Health Implications

Airborne contaminants can pose serious health threats to wildlife and humans, as some of these compounds tend to "biomagnify" in the food chain, ultimately leading to toxic impacts. A briefing (pdf, 61 KB) provided by the NPS Office of Public Health offers perspective on how to interpret WACAP results in the context of human health.

Workshops: Pre & Post – WACAP

Pre – The 2001 NPS Air Toxics Seattle Workshop was designed to be a first step to address air toxics in national parks in the western U.S.
Post – In light of WACAP findings, regionally-held interagency contaminants workshops are facilitating communication, fostering research and collaborative monitoring initiatives on toxics in the environment, and furthering understanding of the effects of airborne contaminants.  more workshop details»

Data Quality

The WACAP Quality Assurance Project Plan (pdf, 3.6 MB) ensures that data collected conform with WACAP data quality objectives and that analyses adhere to precision and accuracy standards.

updated on 2/04/2011   I   I  Email: Webmaster