About NADP

The National Atmospheric Deposition Program (NADP) monitors precipitation chemistry.

The program is a cooperative effort between many different groups, including federal, state, tribal and local governmental agencies, educational institutions, private companies, and non-governmental agencies.


In 1977, U.S. State Agricultural Experiment Stations (SAES) organized a project, later titled the National Atmospheric Deposition Program (NADP), to measure atmospheric deposition and study its effects on the environment.

Sites in the NADP precipitation chemistry network began operations in 1978 with the goal of providing data on the amounts, trends, and geographic distributions of acids, nutrients, and base cations in precipitation. The network grew rapidly in the early 1980s. Much of this expansion was funded by the National Acid Precipitation Assessment Program (NAPAP), established in 1981 to improve understanding of the causes and effects of acidic precipitation. Reflecting the federal NAPAP role in the NADP, the network name was changed to NADP National Trends Network (NTN). Today, the NADP is SAES National Research Support Project – 3. The NTN network currently has 260 sites.

A second network, the Atmospheric Integrated Research Monitoring Network (AIRMoN) joined the NADP in 1992 and operated until 2019. Although measuring the same chemicals as NTN, AIRMoN sampled daily rather than weekly. These higher resolution samples enhance researchers’ ability to evaluate how emissions affect precipitation chemistry using computer simulations of atmospheric transport and pollutant removal. This network also evaluated alternative sample collection and preservation methods. The network was discontinued in September 2019.

A third network, the Mercury Deposition Network (MDN) joined the NADP in 1996, and currently has about 85 sites in the United States and Canada. All MDN samples are analyzed for total mercury. Up until May 2022, some sites were analyzed for the more toxic methyl mercury. Fish consumption advisories for mercury exist in almost every state in the country warning people to limit consumption of fish, and a few states also have wildlife consumption advisories for mercury. Researchers use MDN data to evaluate the role of precipitation as a source of mercury in these water bodies.

The Atmospheric Mercury Network (AMNet), joined NADP in 2009. This network measures atmospheric mercury fractions which contribute to dry and total mercury deposition. At AMNet’s 11 sites, automated continuous measuring systems collect concentrations of atmospheric mercury species, concentrations of total mercury in precipitation, and meteorological measurements. Data is collected with standardized methods, with quality assured data archived in an online data base.

The Ammonia Monitoring Network (AMoN) joined NADP in 2010. It began as a special study in 2007, and now comprises about 90 monitoring locations. The AMoN is the only network providing a consistent, long-term record of ammonia gas concentrations across the United States.

The Mercury Litterfall Network (MLN) joined NADP in 2021. It began as a special initiative in 2007, and continued as a transitional network until it was approved in 2021. The MLN provides an estimate of an important component of mercury dry deposition to a forested landscape.

In March 2018, NADP moved their Program Office from their longtime home at the University of Illinois Urbana-Champaign to the Wisconsin State Laboratory of Hygiene at the University of Wisconsin-Madison. Following the move of the Program Office, the two supporting labs previously known as the Central Analytical Laboratory (CAL) followed in June 2018 and the Mercury Analytical Laboratory (HAL) in June 2019. The labs were renamed as the NADP Analytical Laboratory (NAL) in May 2023,

For more information about NADP’s early history, please see Thirty Years Down and a Century to Go, from a presentation by Ellis Cowling.

Recognition Awards

Starting in 2017, the Executive Committee approved the creation of two awards to recognize contributions to the National Atmospheric Deposition Program. The Past Chair accepts nominations for awards for exceptional contributions to NADP and presents candidates to the Executive Committee for approval. Awards are commonly given to NADP members who are retiring or leaving the NADP after many years of service to the organization. There may be multiple recipients of each award every year. The awards are presented by the Chair at the Annual Fall Meeting and Scientific Symposium.

Ellis B. Cowling Lifetime Achievement Award

The Ellis B. Cowling Lifetime Achievement Award is presented for dedicated service to NADP as a significant part of one’s career.

Starting in 1975, Ellis Cowling led a group of scientists in creating the National Atmospheric Deposition Program. Through his early leadership, NADP was successful in increasing scientific and public understanding of changes to the environment and the sustainability of ecosystems.

Award Recipients

  • 2022: Donna B. Schwede(U.S. Environmental Protection Agency)
    For exceptional leadership as Chair of the NADP organization and outstanding advancement of atmospheric science.
  • 2022: Robert S. Larson (National Atmospheric Deposition Program)
    For dedicated service in data management and dissemination for the NADP and its collaborators.
  • 2019: Robert C. Brunette (Eurofins Frontier Global Sciences, LLC)
    For invaluable contributions to create the Mercury Deposition Network and leadership excellence in implementation by Eurofins Frontier Global Sciences, LLC.
  • 2018: Gary G. Lear (U.S. Environmental Protection Agency)
    For dedication of his career to the advancement of NADP operations, infrastructure, research, and data quality.
  • 2018: Mark A. Nilles (U.S. Geological Survey)
    For dedication of his career to the advancement of NADP operations, infrastructure, research, and data quality.

Van Bowersox Meritorious Service Award

The Van Bowersox Meritorious Service Award is presented for significant, lasting contributions to NADP networks, science committees, and scientific discovery.

Van Bowersox spent close to two decades with NADP, first as the CAL Director, and then as the Program Coordinator when the Coordination Office was moved to the University of Illinois to become the Program Office. Van’s leadership during those transitional years was an important contribution to the continued success of the NADP.

Award Recipients

  • 2023: Eric M. Prestbo (Tekran Instruments Corp.).
    For his significant contributions to the advancement of mercury deposition monitoring and science.
  • 2021: Pamela E. Padgett (U.S. Forest Service).
    For her leadership and contributions to the advancement of the NADP with regard to educational outreach and ecological studies.
  • 2019: Tamara F. Blett (National Park Service).
    In recognition of her leadership in NADP and advancement of critical loads science.
  • 2018: Martin R. Risch (U.S. Geological Survey).
    For significant contributions to the advancement of mercury deposition science.
  • 2017: Richard S. Artz (National Oceanic and Atmospheric Administration).
    For significant contributions to the enhancement of NADP operations, data quality, and national and international recognition.

Operator Recognition Awards

Starting in 2021, the Executive Committee approved the creation of the Operator Recognition Award to recognize site operators who consistently go above and beyond the requirements of their job to ensure their sites produce the highest quality data possible. Open nominations are accepted for the award. The award is presented by the nominator at the Joint meeting at either the Spring or Fall meetings.

Award Recipients
The NADP Foundation

Your gift to the NADP Foundation supports a greater understanding of atmospheric deposition and its effect on ecosystems and the public. Since 1978, the NADP has measured the spatial and temporal trends of atmospheric deposition across North America and beyond. The NADP serves a vast community of researchers, policy makers, educators, and the public with free, quality-assured, monitoring results. NADP is a public nonprofit association of supporters and data users interested in understanding atmospheric deposition and its effects on ecosystems and the public. Help support the continued operation of the NADP networks through a donation to the NADP Foundation. Your support will help ensure continuing access to the robust spatial and temporal data set, support the development of new initiatives, and advance NADP outreach and reporting tools.

Your generous support ensures continuing access to the robust data sets, funds the development of new research and initiatives, and advances the education outreach and reporting tools of the program.

The foundation gives you the opportunity to support the work of the NADP; a public nonprofit association of supporters and data users that are dedicated to identifying and assessing deposition impacts on the environment. The NADP Foundation is administered by the University of Wisconsin Foundation and can be accessed at the following link:

WSLH National Atmospheric Deposition Program Fund – 112900215

With your generous charitable gift, we can continue to provide quality atmospheric deposition data now and into the future!


If you have questions about gift options and foundation details please contact the NADP Coordinator David Gay at David.Gay@slh.wisc.edu.




    ABOUT NADP (4 videos)

NADP @ 40 (9 videos)

NADP celebrated 40 years in 2018

NADP @ 40 Mashup

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Scotty Dossett – NADP Site Liaison 1986-2005

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David Gay – NADP Coordinator

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Jane Rothert

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Van Bowersox – NADP Coordinator 1997-2008

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Gary Stensland – CAL Director 1978-1989

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Chris Lehmann – CAL Director 2007-2018

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Molly Wolosyzn Outreach Coordinator 2014-2017

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