Nutrients and Eutrophication Active
Agriculture, Nutrients, and the Nation's Waters
Affecting every component of the hydrologic system
Like people, plants need nutrients, but too much of a good thing can be a problem. Nutrients, such as nitrogen and phosphorus, occur naturally, but most of the nutrients in our waterways come from human activities and sources—fertilizers, wastewater, automobile exhaust, animal waste. The USGS investigates the source, transport, and fate of nutrients and their impacts on the world around us.
Featured: Nutrient yields in the Mississippi/Atchafalaya River Basin
A new USGS study estimates total nitrogen (N) and total phosphorus (P) yields from catchments throughout the Mississippi/Atchafalaya River Basin, which drains about 41% of the conterminous U.S. Results could assist nutrient reduction strategies.
BACKGROUND
Nutrients are essential for plant growth, but the overabundance of nutrients in water can have many harmful health and environmental effects. An overabundance of nutrients—primarily nitrogen and phosphorus—in water starts a process called eutrophication. Algae feed on the nutrients, growing, spreading, and turning the water green. Algae blooms can smell bad, block sunlight, and even release toxins in some cases. When the algae die, they are decomposed by bacteria—this process consumes the oxygen dissolved in the water and needed by fish and other aquatic life to "breathe". If enough oxygen is removed, the water can become hypoxic, where there is not enough oxygen to sustain life, creating a "dead zone".
WHAT ARE NUTRIENTS?
Nutrients are chemical elements found in the food that plants and animals need to grow and survive. Although there are many kinds of nutrients, two of the most important and abundant are nitrogen and phosphorus. Nitrogen and phosphorus occur in a variety of forms, or species, and the species present can change as they move between the air, water, and soil.
- AMMONIA (NH3) and AMMONIUM (NH4+) are among the primary forms of nitrogen in natural waters. Ammonia can be toxic to fish. It is also soluble in water and relatively unstable in most environments. Ammonia is easily transformed into nitrate (NO3-) in waters that contain sufficient dissolved oxygen or into nitrogen gas in waters that have no dissolved oxygen.
- NITRATE (NO3-) is another primary form of nitrogen in lakes and streams. Nitrate is verysoluble in water and is stable over a wide range of environmental conditions. It is readily transported in groundwater and streams. An excessive amount of nitrate in drinking water can cause health problems.
- PHOSPHATES (containing PO43−) are the most common form of phosphorus in natural waters. Phosphates are only moderately soluble and, compared to nitrate, are not very mobile in soils and groundwater. Phosphates tend to remain attached to soil particles, but erosion can transport considerable amounts of phosphate to streams and lakes.
Learn more about nutrients in our Nation's surface water and groundwater.
USGS Circular 1350
WHAT HAPPENS WHEN THERE ARE EXCESSIVE NUTRIENTS?
Eutrophication is a natural process that results from accumulation of nutrients in lakes or other bodies of water. Algae that feed on nutrients grow into unsightly scum on the water surface, decreasing recreational value and clogging water-intake pipes. Decaying mats of dead algae can produce foul tastes and odors in the water; their decay by bacteria consumes dissolved oxygen from the water, sometimes causing fish kills. Human activities can accelerate eutrophication by increasing the rate at which nutrients enter the water. Algal growth is usually limited by the available supply of either phosphate or nitrate, and we say that a water body is nitrogen limited if the ratio of nitrogen species to phosphorus species (N:P) is low, or is phosphorus limited if N:P is high.
Harmful algal blooms (HABs) are can be caused by many different types of algae in freshwater ecosystems, and can be triggered by nutrient enrichment. The most frequent and severe blooms typically are caused by cyanobacteria, the only known freshwater algae with the potential for production of toxins potent enough to harm human health. CyanoHABs can threaten human and aquatic ecosystem health. Economic damages related to cyanoHABs include the loss of recreational revenue, decreased property values, and increased drinking-water treatment costs.
RELATED USGS RESEARCH
The USGS works extensively across the country on a variety of aspects related to nutrients and eutrophication. Explore the related projects tab for some examples or click the links below.
- Agriculture and the Quality of the Nation's Waters
- Regional Stream Quality Assessments
- SPARROW modeling: Estimating nutrient, sediment, and dissolved solids transport
- Harmful Algal Blooms
- Effects of Nutrient Enrichment on Stream Ecosystems
- Nutrient Loading for the Mississippi River and Subbasins
- Water-Quality Benchmarks, Including Nutrient Criteria
ADDITIONAL RESOURCES
U.S. Environmental Protection Agency
Natural Resources Conservation Service
Nutrients can come from many areas, but mostly they are associated with runoff from agricultural applications. Here are a few studies that relate to nutrients.
Agriculture and the Quality of the Nation's Waters
Below are data or web applications related to USGS research on nutrients.
Below are a few videos and images related to nutrients and eutrophication.
Follow the links below to USGS publications on nutrients and the quality of our nation's waters.
Understanding the influence of nutrients on stream ecosystems in agricultural landscapes
Nitrate in the Mississippi River and its tributaries, 1980 to 2008: Are we making progress?
The quality of our nation's waters: Nutrients in the nation's streams and groundwater, 1992-2004
Nutrients in the nation's streams and groundwater: National findings and implications
Nitrate Loads and Concentrations in Surface-Water Base Flow and Shallow Groundwater for Selected Basins in the United States, Water Years 1990-2006
The influence of nutrients and physical habitat in regulating algal biomass in agricultural streams
Changes in streamflow and the flux of nutrients in the Mississippi-Atchafalaya River Basin, USA, 1980-2007
Development and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001
Predicting unsaturated zone nitrogen mass balances in agricultural settings of the United States
Nitrate in groundwater of the United States, 1991-2003
Nutrient Trends in Streams and Rivers of the United States, 1993-2003
Redox processes and water quality of selected principal aquifer systems
Decadal-scale changes of nitrate in ground water of the United States, 1988-2004
Below are data or web applications related to USGS research on nutrients.
There are numerous software packages scientists use to investigate water quality and pollution transport. Here are a few examples of applications USGS uses.
See what is newsworthy concerning water-quality in the Nation's lakes and rivers.
What's In Your Stream? Get Online to Find Out!
A new update to an online interactive tool for learning about pesticides, nutrients, and overall stream health in major regions of the U.S. is available from the U.S. Geological Survey’s Regional Stream Quality Assessment.
- Overview
Like people, plants need nutrients, but too much of a good thing can be a problem. Nutrients, such as nitrogen and phosphorus, occur naturally, but most of the nutrients in our waterways come from human activities and sources—fertilizers, wastewater, automobile exhaust, animal waste. The USGS investigates the source, transport, and fate of nutrients and their impacts on the world around us.
Featured: Nutrient yields in the Mississippi/Atchafalaya River BasinA new USGS study estimates total nitrogen (N) and total phosphorus (P) yields from catchments throughout the Mississippi/Atchafalaya River Basin, which drains about 41% of the conterminous U.S. Results could assist nutrient reduction strategies.
BACKGROUND
Nutrients are essential for plant growth, but the overabundance of nutrients in water can have many harmful health and environmental effects. An overabundance of nutrients—primarily nitrogen and phosphorus—in water starts a process called eutrophication. Algae feed on the nutrients, growing, spreading, and turning the water green. Algae blooms can smell bad, block sunlight, and even release toxins in some cases. When the algae die, they are decomposed by bacteria—this process consumes the oxygen dissolved in the water and needed by fish and other aquatic life to "breathe". If enough oxygen is removed, the water can become hypoxic, where there is not enough oxygen to sustain life, creating a "dead zone".
WHAT ARE NUTRIENTS?
Nutrients are chemical elements found in the food that plants and animals need to grow and survive. Although there are many kinds of nutrients, two of the most important and abundant are nitrogen and phosphorus. Nitrogen and phosphorus occur in a variety of forms, or species, and the species present can change as they move between the air, water, and soil.
- AMMONIA (NH3) and AMMONIUM (NH4+) are among the primary forms of nitrogen in natural waters. Ammonia can be toxic to fish. It is also soluble in water and relatively unstable in most environments. Ammonia is easily transformed into nitrate (NO3-) in waters that contain sufficient dissolved oxygen or into nitrogen gas in waters that have no dissolved oxygen.
- NITRATE (NO3-) is another primary form of nitrogen in lakes and streams. Nitrate is verysoluble in water and is stable over a wide range of environmental conditions. It is readily transported in groundwater and streams. An excessive amount of nitrate in drinking water can cause health problems.
- PHOSPHATES (containing PO43−) are the most common form of phosphorus in natural waters. Phosphates are only moderately soluble and, compared to nitrate, are not very mobile in soils and groundwater. Phosphates tend to remain attached to soil particles, but erosion can transport considerable amounts of phosphate to streams and lakes.
Learn more about nutrients in our Nation's surface water and groundwater.
USGS Circular 1350WHAT HAPPENS WHEN THERE ARE EXCESSIVE NUTRIENTS?
Eutrophication is a natural process that results from accumulation of nutrients in lakes or other bodies of water. Algae that feed on nutrients grow into unsightly scum on the water surface, decreasing recreational value and clogging water-intake pipes. Decaying mats of dead algae can produce foul tastes and odors in the water; their decay by bacteria consumes dissolved oxygen from the water, sometimes causing fish kills. Human activities can accelerate eutrophication by increasing the rate at which nutrients enter the water. Algal growth is usually limited by the available supply of either phosphate or nitrate, and we say that a water body is nitrogen limited if the ratio of nitrogen species to phosphorus species (N:P) is low, or is phosphorus limited if N:P is high.
Harmful algal blooms (HABs) are can be caused by many different types of algae in freshwater ecosystems, and can be triggered by nutrient enrichment. The most frequent and severe blooms typically are caused by cyanobacteria, the only known freshwater algae with the potential for production of toxins potent enough to harm human health. CyanoHABs can threaten human and aquatic ecosystem health. Economic damages related to cyanoHABs include the loss of recreational revenue, decreased property values, and increased drinking-water treatment costs.
RELATED USGS RESEARCH
The USGS works extensively across the country on a variety of aspects related to nutrients and eutrophication. Explore the related projects tab for some examples or click the links below.
- Agriculture and the Quality of the Nation's Waters
- Regional Stream Quality Assessments
- SPARROW modeling: Estimating nutrient, sediment, and dissolved solids transport
- Harmful Algal Blooms
- Effects of Nutrient Enrichment on Stream Ecosystems
- Nutrient Loading for the Mississippi River and Subbasins
- Water-Quality Benchmarks, Including Nutrient Criteria
ADDITIONAL RESOURCES
U.S. Environmental Protection Agency
Natural Resources Conservation Service
- Science
Nutrients can come from many areas, but mostly they are associated with runoff from agricultural applications. Here are a few studies that relate to nutrients.
Agriculture and the Quality of the Nation's Waters
Intensive studies by the USGS National Water-Quality Assessment (NAWQA) Project in agricultural areas provide insight into how agricultural activities have altered the natural flow of water and the way that agricultural chemicals enter streams and aquifers, and in particular how nutrients affect algal and invertebrate communities in agricultural streams. - Data
Below are data or web applications related to USGS research on nutrients.
- Multimedia
Below are a few videos and images related to nutrients and eutrophication.
- Publications
Follow the links below to USGS publications on nutrients and the quality of our nation's waters.
Understanding the influence of nutrients on stream ecosystems in agricultural landscapes
Sustaining the quality of the Nation’s water resources and the health of our diverse ecosystems depends on the availability of sound water-resources data and information to develop effective, science-based policies. Effective management of water resources also brings more certainty and efficiency to important economic sectors. Taken together, these actions lead to immediate and long-term economic,AuthorsMark D. Munn, Jeffrey W. Frey, Anthony J. Tesoriero, Robert W. Black, John H. Duff, Kathy Lee, Terry R. Maret, Christopher A. Mebane, Ian R. Waite, Ronald B. ZeltFilter Total Items: 54Nitrate in the Mississippi River and its tributaries, 1980 to 2008: Are we making progress?
Changes in nitrate concentration and flux between 1980 and 2008 at eight sites in the Mississippi River basin were determined using a new statistical method that accommodates evolving nitrate behavior over time and produces flow-normalized estimates of nitrate concentration and flux that are independent of random variations in streamflow. The results show that little consistent progress has been mAuthorsLori A. Sprague, Robert M. Hirsch, Brent T. AulenbachThe quality of our nation's waters: Nutrients in the nation's streams and groundwater, 1992-2004
National Findings and Their ImplicationsAlthough the use of artificial fertilizer has supported increasing food production to meet the needs of a growing population, increases in nutrient loadings from agricultural and, to a lesser extent, urban sources have resulted in nutrient concentrations in many streams and parts of aquifers that exceed standards for protection of human health and (or) aquatAuthorsNeil M. Dubrovsky, Karen R. Burow, Gregory M. Clark, JoAnn M. Gronberg, Pixie A. Hamilton, Kerie J. Hitt, David K. Mueller, Mark D. Munn, Bernard T. Nolan, Larry J. Puckett, Michael G. Rupert, Terry M. Short, Norman E. Spahr, Lori A. Sprague, William G. WilberNutrients in the nation's streams and groundwater: National findings and implications
A comprehensive national analysis of the distribution and trends of nutrient concentrations in streams and groundwater from 1992 through 2004 is provided by the National Water-Quality Assessment (NAWQA) Program of the United States Geological Survey (USGS). Findings describe the distribution and causes of varying nutrient concentrations in streams and groundwater throughout the Nation and examineAuthorsNeil M. Dubrovsky, Pixie A. HamiltonNitrate Loads and Concentrations in Surface-Water Base Flow and Shallow Groundwater for Selected Basins in the United States, Water Years 1990-2006
Hydrograph separation was used to determine the base-flow component of streamflow for 148 sites sampled as part of the National Water-Quality Assessment program. Sites in the Southwest and the Northwest tend to have base-flow index values greater than 0.5. Sites in the Midwest and the eastern portion of the Southern Plains generally have values less than 0.5. Base-flow index values for sites in thAuthorsNorman E. Spahr, Neil M. Dubrovsky, JoAnn M. Gronberg, O. Lehn Franke, David M. WolockThe influence of nutrients and physical habitat in regulating algal biomass in agricultural streams
This study examined the relative influence of nutrients (nitrogen and phosphorus) and habitat on algal biomass in five agricultural regions of the United States. Sites were selected to capture a range of nutrient conditions, with 136 sites distributed over five study areas. Samples were collected in either 2003 or 2004, and analyzed for nutrients (nitrogen and phosphorous) and algal biomass (chlorAuthorsMark D. Munn, Jeffrey W. Frey, Anthony J. TesorieroChanges in streamflow and the flux of nutrients in the Mississippi-Atchafalaya River Basin, USA, 1980-2007
Nutrients and freshwater delivered by the Mississippi and Atchafalaya Rivers drive algal production in the northern Gulf of Mexico, which eventually results in the widespread occurrence of hypoxic bottom waters along the Louisiana and Texas coast. Researchers have demonstrated a relation between the extent of the hypoxic zone and the magnitude of streamflow, nutrient fluxes, and nutrient concentraAuthorsWilliam A. Battaglin, Brent T. Aulenbach, Aldo Vecchia, Herbert T. BuxtonDevelopment and Application of Regression Models for Estimating Nutrient Concentrations in Streams of the Conterminous United States, 1992-2001
Data collected for the U.S. Geological Survey National Water-Quality Assessment program from 1992-2001 were used to investigate the relations between nutrient concentrations and nutrient sources, hydrology, and basin characteristics. Regression models were developed to estimate annual flow-weighted concentrations of total nitrogen and total phosphorus using explanatory variables derived from curreAuthorsNorman E. Spahr, David K. Mueller, David M. Wolock, Kerie J. Hitt, JoAnn M. GronbergPredicting unsaturated zone nitrogen mass balances in agricultural settings of the United States
Unsaturated zone N fate and transport were evaluated at four sites to identify the predominant pathways of N cycling: an almond [Prunus dulcis (Mill.) D.A. Webb] orchard and cornfield (Zea mays L.) in the lower Merced River study basin, California; and corn–soybean [Glycine max (L.) Merr.] rotations in study basins at Maple Creek, Nebraska, and at Morgan Creek, Maryland. We used inverse modeling wAuthorsBernard T. Nolan, Larry J. Puckett, Liwang Ma, Christopher T. Green, E. Randall Bayless, Robert W. MaloneNitrate in groundwater of the United States, 1991-2003
An assessment of nitrate concentrations in groundwater in the United States indicates that concentrations are highest in shallow, oxic groundwater beneath areas with high N inputs. During 1991-2003, 5101 wells were sampled in 51 study areas throughout the U.S. as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) program. The well networks reflect the existing used resourAuthorsKaren R. Burow, Bernard T. Nolan, Michael G. Rupert, Neil M. DubrovskyNutrient Trends in Streams and Rivers of the United States, 1993-2003
Trends in streamflow and concentrations and loads of total phosphorus, total nitrogen, and nitrate were determined for the period from 1993 to 2003 in selected streams and ricers of the United States. Flow-adjusted trends in concentration (the trends that would have occurred in the absence of natural chances in streamflow), non-flow-adjusted trends in concentration (the trends resulting from bothAuthorsLori A. Sprague, David K. Mueller, Gregory E. Schwarz, David L. LorenzRedox processes and water quality of selected principal aquifer systems
Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen, nitrate, and sulAuthorsP. B. McMahon, F. H. ChapelleDecadal-scale changes of nitrate in ground water of the United States, 1988-2004
This study evaluated decadal-scale changes of nitrate concentrations in groundwater samples collected by the USGS National Water-Quality Assessment Program from 495 wells in 24 well networks across the USA in predominantly agricultural areas. Each well network was sampled once during 1988-1995 and resampled once during 2000-2004. Statistical tests of decadal-scale changes of nitrate concentrationsAuthorsMichael G. Rupert - Web Tools
Below are data or web applications related to USGS research on nutrients.
- Software
There are numerous software packages scientists use to investigate water quality and pollution transport. Here are a few examples of applications USGS uses.
- News
See what is newsworthy concerning water-quality in the Nation's lakes and rivers.
What's In Your Stream? Get Online to Find Out!
A new update to an online interactive tool for learning about pesticides, nutrients, and overall stream health in major regions of the U.S. is available from the U.S. Geological Survey’s Regional Stream Quality Assessment.