The National Atmospheric Deposition Program (NADP) is a multi-partner atmospheric monitoring program that measures the concentrations and deposition of atmospheric constituents across North America. The USGS has been an NADP partner agency since 1981 and participates by providing funds for 82 National Trend Network (NTN) sites.
Linking transit times to catchment sensitivity in western U.S.

Short transit times—the time between entry of a water molecule into the ground surface and when it exits the catchment—is a key reason why western U.S. high-elevation catchments are highly sensitive to atmospheric pollution and climate change.
Quick Links
The National Atmospheric Deposition Program (NADP) monitors precipitation chemistry through five monitoring networks. USGS supports monitoring sites within the National Trends Network and the Mercury Deposition Network.
The National Atmospheric Deposition Program (NADP) operates five monitoring networks for various constituents of which the National Trends Network (NTN) is the largest with 263 sites where the major ions in precipitation are measured weekly. The U.S. Geological Survey (USGS) has been an NADP partner agency since 1981 and participates by providing funds for 82 NTN sites.
► More about the NADP data, program, and networks
Data from the NADP networks are used to track trends and examine spatial patterns in atmospheric deposition of constituents that include nitrogen, sulfur, mercury, calcium, and others. Many of these constituents are naturally present in the atmosphere but also originate in part as air pollutant emissions from human activities such as from power plants and vehicles. Clean air policies implemented under the Clean Air Act, as part of global treaties, and by other regulations typically set targets for reducing emissions, which are tracked by NADP measurements. In this manner, there is a close link between science, policy, and management among NADP partners. The identical field sampling protocols and equipment and analyses by one laboratory using the same methods facilitates comparisons across sites and highlights the value of a multi-partner monitoring program.
Below are data or web applications associated with National Atmospheric Deposition Program (NADP).
Data release for journal article "Atmospheric mercury deposition to forests in the eastern USA"
Since 1985, the NADP has created annual gradient maps of precipitation-weighted mean concentrations and deposition for several different parameters.
Slider maps showing the 2018 to 1985 difference in concentrations and deposition for pH, sulfate, and nitrogen are linked below. You can use the slider to compare the two years side by side, or view either year in full.
Scientists use National Atmospheric Deposition Program (NADP) data to investigate nitrogen sources to watersheds and estuaries, ecosystem effects of pollutant deposition, and results of implementation of clean air policies.
Atmospheric Deposition Program of the U.S. Geological Survey
Changes in climate and land cover affect seasonal streamflow forecasts in the Rio Grande headwaters
Inorganic nitrogen wet deposition gradients in the Denver-Boulder metropolitan area and Colorado Front Range – Preliminary implications for Rocky Mountain National Park and interpolated deposition maps
Response of water chemistry and young-of-year brook trout to channel and watershed liming in streams showing lagging recovery from acidic deposition
It is raining plastic
What goes up must come down: Integrating air and water quality monitoring for nutrients
Linking transit times to catchment sensitivity to atmospheric deposition of acidity and nitrogen in mountains of the western United States
Influence of climate on alpine stream chemistry and water sources
Long-term changes in soil and stream chemistry across an acid deposition gradient in the northeastern United States
Spatial and temporal variation in sources of atmospheric nitrogen deposition in the Rocky Mountains using nitrogen isotopes
Spatial patterns and temporal changes in atmospheric-mercury deposition for the midwestern USA, 2001–2016
The response of soil and stream chemistry to decreases in acid deposition in the Catskill Mountains, New York, USA
Precipitation collector bias and its effects on temporal trends and spatial variability in National Atmospheric Deposition Program/National Trends Network data
- Overview
The National Atmospheric Deposition Program (NADP) is a multi-partner atmospheric monitoring program that measures the concentrations and deposition of atmospheric constituents across North America. The USGS has been an NADP partner agency since 1981 and participates by providing funds for 82 National Trend Network (NTN) sites.
Linking transit times to catchment sensitivity in western U.S.Short transit times—the time between entry of a water molecule into the ground surface and when it exits the catchment—is a key reason why western U.S. high-elevation catchments are highly sensitive to atmospheric pollution and climate change.
Quick LinksThe National Atmospheric Deposition Program (NADP) monitors precipitation chemistry through five monitoring networks. USGS supports monitoring sites within the National Trends Network and the Mercury Deposition Network.
The National Atmospheric Deposition Program (NADP) operates five monitoring networks for various constituents of which the National Trends Network (NTN) is the largest with 263 sites where the major ions in precipitation are measured weekly. The U.S. Geological Survey (USGS) has been an NADP partner agency since 1981 and participates by providing funds for 82 NTN sites.
► More about the NADP data, program, and networks
Data from the NADP networks are used to track trends and examine spatial patterns in atmospheric deposition of constituents that include nitrogen, sulfur, mercury, calcium, and others. Many of these constituents are naturally present in the atmosphere but also originate in part as air pollutant emissions from human activities such as from power plants and vehicles. Clean air policies implemented under the Clean Air Act, as part of global treaties, and by other regulations typically set targets for reducing emissions, which are tracked by NADP measurements. In this manner, there is a close link between science, policy, and management among NADP partners. The identical field sampling protocols and equipment and analyses by one laboratory using the same methods facilitates comparisons across sites and highlights the value of a multi-partner monitoring program.
- Data
Below are data or web applications associated with National Atmospheric Deposition Program (NADP).
Data release for journal article "Atmospheric mercury deposition to forests in the eastern USA"
Data for mercury concentrations in annual litterfall samples and associated litterfall mass will be released. The litterfall samples were collected at selected National Atmospheric Deposition Program sites in 2007-2009 and 2012-2014. - Multimedia
Since 1985, the NADP has created annual gradient maps of precipitation-weighted mean concentrations and deposition for several different parameters.
Slider maps showing the 2018 to 1985 difference in concentrations and deposition for pH, sulfate, and nitrogen are linked below. You can use the slider to compare the two years side by side, or view either year in full.
- Publications
Scientists use National Atmospheric Deposition Program (NADP) data to investigate nitrogen sources to watersheds and estuaries, ecosystem effects of pollutant deposition, and results of implementation of clean air policies.
Atmospheric Deposition Program of the U.S. Geological Survey
No abstract available.AuthorsMark A. NillesFilter Total Items: 151Changes in climate and land cover affect seasonal streamflow forecasts in the Rio Grande headwaters
Seasonal streamflow forecast bias, changes in climate, snowpack, and land cover, and the effects of these changes on relations between basin‐wide snowpack, SNOw TELemetry (SNOTEL) station snowpack, and seasonal streamflow were evaluated in the headwaters of the Rio Grande, Colorado. Results indicate that shifts in the seasonality of precipitation and changing climatology are consistent with periodAuthorsColin A. Penn, David W. Clow, Graham A. Sexstone, Sheila F. MurphyInorganic nitrogen wet deposition gradients in the Denver-Boulder metropolitan area and Colorado Front Range – Preliminary implications for Rocky Mountain National Park and interpolated deposition maps
For the first time in the 40-year history of the National Atmospheric Deposition Program / National Trends Network (NADP/NTN), a unique urban-to-rural transect of wet deposition monitoring stations were operated as part of the NTN in 2017 to quantify reactive inorganic nitrogen wet deposition for adjacent urban and rural, montane regions. The transect of NADP stations (sites) was used to collectAuthorsGregory A. Wetherbee, Katherine Benedict, Sheila F. Murphy, Emily ElliottResponse of water chemistry and young-of-year brook trout to channel and watershed liming in streams showing lagging recovery from acidic deposition
Reductions in sulfur emissions have initiated chemical recovery of surface waters impacted by acidic deposition in the Adirondack region of New York State. However, acidified streams remain common in the region, which limits recovery of brook trout (Salvelinus fontinalis) populations. To investigate liming as a method to accelerate recovery of brook trout, the channels of two acidified streams werAuthorsDaniel C Josephson, Gregory B. Lawrence, Scott D. George, Jason Siemion, Barry P. Baldigo, Clifford E. KraftIt is raining plastic
Atmospheric deposition samples were collected using the National Atmospheric Deposition Program / National Trends Network (NADP/NTN) at 6 sites in the Denver-Boulder urban corridor and 2 adjacent sites in the Colorado Front Range. Weekly wet-only atmospheric deposition samples collected at these sites during winter-summer of 2017 were filtered (0.45 micrometers, polyethersulfone) to obtain particAuthorsGregory A. Wetherbee, Austin K. Baldwin, James F. RanvilleWhat goes up must come down: Integrating air and water quality monitoring for nutrients
Excess nitrogen and phosphorus (“nutrients”) loadings continue to affect ecosystem function and human health across the U.S. Our ability to connect atmospheric inputs of nutrients to aquatic end points remains limited due to uncoupled air and water quality monitoring. Where connections exist, the information provides insights about source apportionment, trends, risk to sensitive ecosystems, and efAuthorsHelen M Amos, Chelcy Miniat, Jason A. Lynch, Jana Compton, Pamela H. Templer, Lori A. Sprague, Denice M Shaw, Douglas A. Burns, Anne Rea, Dave Whitall, LaToya Myles, David A. Gay, Mark A. Nilles, John W. Walker, Anita K Rose, Jerad Bales, Jeffrey R. Deacon, Rich PouyetLinking transit times to catchment sensitivity to atmospheric deposition of acidity and nitrogen in mountains of the western United States
Transit times are hypothesized to influence catchment sensitivity to atmospheric deposition of acidity and nitrogen (N) because they help determine the amount of time available for infiltrating precipitation to interact with catchment soil and biota. Transit time metrics, including fraction of young water (Fyw) and mean transit time (MTT), were calculated for 11 headwater catchments in mountains oAuthorsDavid W. Clow, Alisa Mast, James O. SickmanInfluence of climate on alpine stream chemistry and water sources
The resilience of alpine/subalpine watersheds may be viewed as the resistance of streamflow or stream chemistry to change under varying climatic conditions, which is governed by the relative size (volume) and transit time of surface and subsurface water sources. Here, we use end‐member mixing analysis in Andrews Creek, an alpine stream in Rocky Mountain National Park, Colorado, from water year 199AuthorsSydney Foks, Edward G. Stets, Kamini Singha, David W. ClowLong-term changes in soil and stream chemistry across an acid deposition gradient in the northeastern United States
Declines in acidic deposition across Europe and North America have led to decreases in surface water acidity and signs of chemical recovery of soils from acidification. To better understand the link between recovery of soils and surface waters, chemical trends in precipitation, soils, and streamwater were investigated in three watersheds representing a depositional gradient from high to low acrossAuthorsJason Siemion, Michael McHale, Gregory B. Lawrence, Douglas A. Burns, Michael R. AntidormiSpatial and temporal variation in sources of atmospheric nitrogen deposition in the Rocky Mountains using nitrogen isotopes
Variation in source areas and source types of atmospheric nitrogen (N) deposition to high-elevation ecosystems in the Rocky Mountains were evaluated using spatially and temporally distributed N isotope data from atmospheric deposition networks for 1995-2016. This unique dataset links N in wet deposition and snowpack to mobile and stationary emissions sources, and enhances understanding of the impaAuthorsLeora Nanus, Donald H. Campbell, Christopher M.B. Lehmann, Alisa MastSpatial patterns and temporal changes in atmospheric-mercury deposition for the midwestern USA, 2001–2016
Spatial patterns and temporal changes in atmospheric-mercury (Hg) deposition were examined in a five-state study area in the Midwestern USA where 32% of the stationary sources of anthropogenic Hg emissions in the continental USA were located. An extensive monitoring record for wet and dry Hg deposition was compiled for 2001–2016, including 4666 weekly precipitation samples at 13 sites and 27 annuaAuthorsMartin R. Risch, Donna M. KenskiThe response of soil and stream chemistry to decreases in acid deposition in the Catskill Mountains, New York, USA
The Catskill Mountains have been adversely impacted by decades of acid deposition, however, since the early 1990s, levels have decreased sharply as a result of decreases in emissions of sulfur dioxide and nitrogen oxides. This study examines trends in acid deposition, stream-water chemistry, and soil chemistry in the southeastern Catskill Mountains. We measured significant reductions in acid deposAuthorsMichael McHale, Douglas A. Burns, Jason Siemion, Michael R. AntidormiPrecipitation collector bias and its effects on temporal trends and spatial variability in National Atmospheric Deposition Program/National Trends Network data
Precipitation samples have been collected by the National Atmospheric Deposition Program's (NADP) National Trends Network (NTN) using the Aerochem Metrics Model 301 (ACM) collector since 1978. Approximately one-third of the NTN ACM collectors have been replaced with N-CON Systems, Inc. Model ADS 00-120 (NCON) collectors. Concurrent data were collected over 6 years at 12 NTN sites using colocated AAuthorsGregory A. Wetherbee