A recent U.S. Geological Survey (USGS) study provides a rare glimpse into how nitrate levels in 22 large rivers across the Nation have changed during the past 65 years. Despite the stabilization of nitrogen inputs in recent decades, there is no evidence of widespread decrease in nitrate levels in rivers.
More on Nitrate Levels
Nitrate levels in large U.S. rivers increased up to fivefold from 1945 to 1980 in intensively managed agricultural areas of the Midwest. The greatest increases in river nitrate levels coincided with increased nitrogen inputs from livestock and agricultural fertilizer, which grew rapidly from 1945 to 1980. In some urbanized areas along the East and West coasts during the same period, river nitrate levels doubled. Since 1980, however, nitrate changes have been smaller because the increase in fertilizer use has decreased in the Midwest and large amounts of farmland have been converted to forest or urban land along the east coast.
Environmental Health Implications
The USGS study includes rivers flowing into the Great Lakes and coastal waters such as Long Island Sound, Delaware River estuary, Chesapeake Bay, San Francisco Bay, and the Gulf of Mexico. High nitrate levels can lead to the formation of zones of low oxygen in coastal waters, which harms fisheries, recreational use, and ecological habitat, causing major economic impacts. High nitrate levels also pose a threat to drinking-water supplies, sometimes resulting in high water-treatment costs.
Long-term monitoring of water quality is essential to track how changes in land use, climate, and water-quality management actions are affecting local streams and rivers and valuable commercial and recreational fisheries in estuaries across the Nation. The USGS National Water-Quality Assessment (NAWQA) Program is working on a comprehensive assessment of nitrate trends from within the past 10 to 40 years at almost 500 small and large river sites across the Nation.
This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) as well as the USGS Hydrologic Research and Development and NAWQA Programs.
Below are other science projects associated with this project.
National Water-Quality Assessment (NAWQA)
Predicting Pesticide Levels in Streams and Rivers—Where is Water Quality at Risk?
New Online Tool Tracks Water Quality in the Nation's Rivers and Streams
Public-Supply Well Pumping Regimes Influence Quality of Water Produced
Small Decadal–Scale Changes in Pesticides in Groundwater
USGS Health-Based Screening Levels Available Online
Below are publications associated with this project.
Regional and temporal differences in nitrate trends discerned from long-term water quality monitoring data
Below are data or web applications associated with this project.
Tracking Water Quality of the Nation's Streams and Rivers
An online graphical data tool provides annual summaries of nutrient and sediment concentrations and loads and streamflow information for 106 sites monitored as part of the USGS National Water-Quality Network for Streams and Rivers.
Below are news stories associated with this project.
- Overview
A recent U.S. Geological Survey (USGS) study provides a rare glimpse into how nitrate levels in 22 large rivers across the Nation have changed during the past 65 years. Despite the stabilization of nitrogen inputs in recent decades, there is no evidence of widespread decrease in nitrate levels in rivers.
The Maumee River flows through northwest Ohio into Lake Erie. Nitrate concentrations in the Maumee River increased rapidly between 1945 and 1980 as nitrogen inputs from fertilizer and livestock increased. Since 1980, changes in nitrate levels have been much smaller because the nitrogen inputs leveled off. Data from Stets and others (2015). More on Nitrate Levels
Nitrate levels in large U.S. rivers increased up to fivefold from 1945 to 1980 in intensively managed agricultural areas of the Midwest. The greatest increases in river nitrate levels coincided with increased nitrogen inputs from livestock and agricultural fertilizer, which grew rapidly from 1945 to 1980. In some urbanized areas along the East and West coasts during the same period, river nitrate levels doubled. Since 1980, however, nitrate changes have been smaller because the increase in fertilizer use has decreased in the Midwest and large amounts of farmland have been converted to forest or urban land along the east coast.
Environmental Health Implications
The USGS study includes rivers flowing into the Great Lakes and coastal waters such as Long Island Sound, Delaware River estuary, Chesapeake Bay, San Francisco Bay, and the Gulf of Mexico. High nitrate levels can lead to the formation of zones of low oxygen in coastal waters, which harms fisheries, recreational use, and ecological habitat, causing major economic impacts. High nitrate levels also pose a threat to drinking-water supplies, sometimes resulting in high water-treatment costs.
Long-term monitoring of water quality is essential to track how changes in land use, climate, and water-quality management actions are affecting local streams and rivers and valuable commercial and recreational fisheries in estuaries across the Nation. The USGS National Water-Quality Assessment (NAWQA) Program is working on a comprehensive assessment of nitrate trends from within the past 10 to 40 years at almost 500 small and large river sites across the Nation.
This research was funded by the USGS Ecosystems Mission Area’s Environmental Health Program (Contaminant Biology and Toxic Substances Hydrology) as well as the USGS Hydrologic Research and Development and NAWQA Programs.
- Science
Below are other science projects associated with this project.
National Water-Quality Assessment (NAWQA)
Our surface water, groundwater, and aquatic ecosystems are priceless resources, used by people across the Nation for drinking, irrigation, industry, and recreation. The National Water-Quality Assessment (NAWQA) Project is a leading source of scientific data and knowledge for development of science-based policies and management strategies to improve and protect our water resources.Predicting Pesticide Levels in Streams and Rivers—Where is Water Quality at Risk?
A new interactive mapping tool predicts likely concentrations for 108 pesticides in streams and rivers across the Nation.New Online Tool Tracks Water Quality in the Nation's Rivers and Streams
A new online graphical data tool that provides annual summaries of nutrient and sediment concentrations and loads and streamflow information is now available from the U.S. Geological Survey (USGS).Public-Supply Well Pumping Regimes Influence Quality of Water Produced
U.S. Geological Survey (USGS) scientists studying the vulnerability of public-supply wells to contamination have identified ways in which the seasonal operation of public-supply wells can affect the quality of water that they produce. By incorporating historical water-quality data into models of fluid flow, USGS scientists were able to estimate the amount of contaminated groundwater reaching a...Small Decadal–Scale Changes in Pesticides in Groundwater
U.S. Geological Survey (USGS) scientists have completed the most comprehensive evaluation to date (2014) of decadal–scale changes in pesticide concentrations in groundwater of the United States. Such assessments are essential for tracking long–term responses to changes in pesticide use and land–management practices.USGS Health-Based Screening Levels Available Online
A U.S. Geological Survey USGS Health-Based Screening Level (HBSL) Web site includes human-health benchmarks for 351 contaminants (79 U.S. Environmental Protection Agency (EPA) Maximum Contaminant Levels (MCLs), 117 EPA Human Health Benchmarks for Pesticides (HHBPs), and 155 USGS HBSLs). The Web site also provides detailed toxicity information used to calculate HBSLs. A comprehensive update of the... - Publications
Below are publications associated with this project.
Regional and temporal differences in nitrate trends discerned from long-term water quality monitoring data
Riverine nitrate (NO3) is a well-documented driver of eutrophication and hypoxia in coastal areas. The development of the elevated river NO3 concentration is linked to anthropogenic inputs from municipal, agricultural, and atmospheric sources. The intensity of these sources has varied regionally, through time, and in response to multiple causes such as economic drivers and policy responses. This sAuthorsEdward G. Stets, Valerie J. Kelly, Charles G. Crawford - Web Tools
Below are data or web applications associated with this project.
Tracking Water Quality of the Nation's Streams and Rivers
An online graphical data tool provides annual summaries of nutrient and sediment concentrations and loads and streamflow information for 106 sites monitored as part of the USGS National Water-Quality Network for Streams and Rivers.
- News
Below are news stories associated with this project.