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This mapper provides results from the largest-ever assessment of water-quality changes in the Nation's streams and rivers. More than 185 million water-quality records from over 600 Federal, State, Tribal, and local organizations were screened as part of this assessment.
Tracking changes in stream quality and investigating the reasons for these changes is crucial for informing management decisions to protect and sustain our valuable water resources.
The mapper shows stream trends in water chemistry (nutrients, pesticides, sediment, carbon, and salinity) and aquatic ecology (fish, invertebrates, and algae) for four time periods: 1972-2012, 1982-2012, 1992-2012, and 2002-2012.
LEFT: A U.S. Geological Survey hydrologic technician collecting a water-quality sample from the Colorado River near the Colorado-Utah state line. Photograph by Nancy Bauch with the U.S. Geological Survey.
Since passage of the Clean Water Act in 1972, Federal, State, and local governments have invested billions of dollars to reduce pollution entering streams and rivers. In order to understand the return on these investments, and to more effectively manage and protect the Nation's water resources in the future, we need to know: Has water quality has been changing over time?
Answering that question is one of the major goals of the U.S. Geological Survey's (USGS) National Water-Quality Assessment project. To support that goal, they have conducted long-term consistent and comparable monitoring on streams and rivers throughout the Nation since 1992. Other USGS programs, as well as many other Federal, State, regional, and local monitoring organizations, also have collected long-term water-quality data to support their own assessments of changing water- quality conditions. For the first time, data from these organizations have been aggregated, screened, standardized, and used to support the most comprehensive assessment of stream-quality trends conducted to date in the United States. Collectively, these trend results will be used to provide insight into how natural features and human activities have contributed to water-quality changes over time in the Nation's streams and rivers.
Trends in water quality and aquatic ecology were evaluated for four time periods: 1972-2012, 1982- 2012, 1992-2012, and 2002-2012. Trends in the water-quality constituents were evaluated for both concentration and load. Concentration is the amount of the constituent in the stream. Load is the mass of the constituent transported past the sampling point in a stream during a period of time.
All of the water-quality and aquatic-ecology trends reported in this mapper are normalized for climatic variability. The specific terminology for the water-quality trends is "flow normalized".
The water-quality and aquatic-ecology constituents included in the analysis were:
[mg/L, milligrams per liter. kg/year, kilograms per year; umohs/cm, micromhos per centimeter; N, nitrogen; P, phosphorus; CaCO3, calcium carbonate; S, sulfate.]
USGS National Water-Quality Assessment Project
USGS Water Quality Information
USGS National Research Program
USGS Water Resources Programs
USGS Science in Your Watershed
USGS Water Mission Area
USGS Climate and Land Use Change Mission Area
USGS Ecosystems Mission Area
USGS Energy and Minerals Mission Area
USGS Environmental Health Mission Area
USGS Natural Hazards Mission Area
USGS Coastal and Marine Geology Program
USGS Energy Resources Program Environmental Aspects of Energy Production and Use
U.S. Environmental Protection Agency (USEPA) homepage
USEPA Water Data and Tools
USEPA Recommended Water Quality Standards
USEPA National Aquatic Resource Surveys
USEPA Pesticide Information
USEPA Ecotoxicology Database for Aquatic Life, Terrestrial Plants, and Wildlife
USEPA Surf Your Watershed
U.S. Department of Agriculture (USDA) homepage
USDA Natural Resources Conservation Service
USDA Conservation Effects Assessment Project (CEAP)
Long-term water-quality monitoring data from the following organizations were included in this analysis:
Alabama Department of Environmental Management • Arkansas Department of Environmental Quality • California Department of Water Resources • California Regional Water Board, Region 5 • California Regional Water Quality Control Board • Westside San Joaquin River Watershed Coalition • City of Thornton • Colorado Department of Public Health and Environment • Littleton and Englewood Wastewater Treatment Plant • Metro Wastewater Reclamation District • Summit Water Quality Committee • The Rivers of Colorado Water Watch Network • Delaware Department of Natural Resources and Environmental Control • District Department of the Environment • Environmental Protection Commission of Hillsborough County • Florida Department of Environmental Protection • Florida Fish and Wildlife Conservation Commission • Leon County Public Works • Loxahatchee River District • Manatee County Environmental Management Department • McGlynn Laboratories Incorporated • Northwest Florida Water Management District • Orange County Environmental Protection • Pinellas County Department of Environmental Management • Seminole County • Southwest Florida Water Management District • St. Johns Water Management District • Suwannee River Water Management District • Georgia Department of Natural Resources • Idaho Department of Environmental Quality • Illinois Environmental Protection Agency • Indiana Department of Environmental Management • Marion County Public Health Department • Wabash River Enhancement Corporation • Des Moines River Water Quality Network • Des Moines Water Works • Iowa Department of Natural Resources • Kansas Department of Health and Environment • Kentucky Department for Natural Resources and Environmental Protection • Louisiana Department of Environmental Quality • Maryland Department of Natural Resources • Michigan Department of Environmental Quality • Metropolitan Council Environmental Services • Minnesota Department of Agriculture • Minnesota Pollution Control Agency • Crowder College, Neosho, Missouri • Montana Department of Environmental Quality • Nebraska Department of Environmental Quality • Nevada Department of Conservation and Natural Resources • New Jersey Department of Environmental Protection • Community Science Institute • North Carolina Department of Environment and Natural Resources • North Dakota Department of Health • Heidelberg University, National Center for Water Quality Research • Ohio Environmental Protection Agency • Oklahoma Water Resources Board • Klamath Tribes Research Station • Oregon Department of Environmental Quality • Oregon, Portland Water Bureau • Pennsylvania Department of Environmental Protection • South Carolina Department of Health and Environmental Control • South Dakota Department of Environmental and Natural Resources • Texas Commission on Environmental Quality • Utah Department of Environmental Quality • Virginia Department of Environmental Quality • Washington State Department of Ecology • West Virginia Department of Environmental Protection • Wisconsin Department of Natural Resources • Ohio River Valley Water Sanitation Commission (ORSANCO) • Susquehanna River Basin Commission • U.S. Bureau of Reclamation • U.S. Environmental Protection Agency • U.S. Geological Survey • U.S. National Park Service
A full list of the 608 Federal, State, Tribal, and local organizations whose data were screened as part of this assessment is available in Oelsner, G.P., Sprague, L.A., Murphy, J.C., Zuellig, R.E., Johnson, H.M., Ryberg, K.R., Falcone, J.A., Stets, E.G., Vecchia, A.V., Riskin, M.L., De Cicco, L.A., Mills, T.J., and Farmer, W.H., 2017, Water- Quality Trends in the Nation's Rivers and Streams 1972-2012-Data Preparation, Statistical Methods, and Trend Results: U.S. Geological Survey Scientific Investigations Report 2017-5006, 136p., https://doi.org/10.3133/sir20175006.
Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
SearchingThe search option allows the user to search for a location such as a city, state, zip code, or general place name.
Navigating the mapThe scroll wheel on the mouse can be used to zoom, and in the upper left area of the tool are "+" and "-" icons to zoom in and out, respectively.
Home LocationThe crosshair button will zoom the map to your location, and the home button will center the US on the map.
Opening a siteClicking on an arrow or circle at a site will bring up a window with details about the site, graphs of the original data and model predictions (for some constituents), and a table of the other trend results at the same site.
Moving site windowReposition the site info pop-up window with the mouse see the rest of the underlying map if necessary.
More site detailsAdditional details about the graphs are available in the FAQs. Additional details about the column headers in the table are available by hovering on the help button for each column header.
Explanation displayThe Explanation box can be collapsed to display more of the mapped area.
Using the ExplanationThe expanded Explanation box explains the arrows and circles that appear for each site, displaying the results from the statistical analysis of trends.
A likelihood-based approach is used to report these trend results. When the trend is "likely up" or "likely down", the trend likelihood value associated with the trend is between 0.85 and 1.0 -- in other words, the chance of the trend occurring in the specified direction is at least an 85 out of 100. When the trend is "somewhat likely up" or "somewhat likely down", the trend likelihood value associated with the trend is between 0.7 and 0.85 -- in other words, the chance of the trend occurring in the specified direction is between 70 and 85 out of 100. When the trend is "about as likely as not", the trend likelihood value associated with the trend is less than 0.7 -- in other words, the chance of the trend being either upward or downward is less than 70 out of 100.
This likelihood-based approach is used as an alternative to the null-hypothesis significance testing (NHST) approach that is often used when reporting water-quality trends. The likelihood-based approach gives people more intuitive information on the certainty of a trend estimate, and provides more evidence of a growing problem or initial clean-up successes. Consider an example where the chance of an upward trend in nitrate concentrations at a site is 80 out of 100 (a trend likelihood value of 0.80). Using the NHST approach and a traditional alpha value of either 0.05 or 0.1, the trend would be reported as nonsignificant. Using the likelihood-based approach, the trend would be reported instead as "somewhat likely up". The NHST approach could lead to a false sense of security because it indicates that there isn't strong proof of a growing problem. The likelihood-based approach indicates instead that it is somewhat likely conditions in the stream are not improving, giving people more information to use when making decisions about watershed management.
For more information on the philosophy of the likelihood-based approach, please see Hirsch and others (2015), "A bootstrap method for estimating uncertainty of water quality trends", at http://dx.doi.org/10.1016/j.envsoft.2015.07.017. Trend likelihood values for nutrients, sediment, salinity, major ions, and carbon were determined using the bootstrap approach in that same report. Trend likelihood values for pesticides and aquatic ecology metrics were determined using the p-value reported from their respective trend tests, using the equation 1-(p-value/2). See Vecchia and others (2008), "Modeling Variability and Trends in Pesticide Concentrations in Streams", at http://onlinelibrary.wiley.com/doi/10.1111/j.1752-1688.2008.00225.x/pdf for more information on calculating p-values in the pesticide models. See Oelsner, G.P., Sprague, L.A., Murphy, J.C., Zuellig, R.E., Johnson, H.M., Ryberg, K.R., Falcone, J.A., Stets, E.G., Vecchia, A.V., Riskin, M.L., De Cicco, L.A., Mills, T.J., and Farmer, W.H., 2017, Water- Quality Trends in the Nation's Rivers and Streams 1972-2012-Data Preparation, Statistical Methods, and Trend Results: U.S. Geological Survey Scientific Investigations Report 2017-5006, 136p., https://doi.org/10.3133/sir20175006. for more information on calculating p-values in the ecology models.
Changing the basemap styleThe "Basemaps" sidebar allows a user to show various geographic information or landscape imagery as a background layer beneath the trend results.
Changing or adding map layersThe "Map Layers" sidebar allows a user to show land use for 1974, 1982, 1992, 2002, or 2012 as a background layer beneath the trend results.
Selecting a constituentThe Constituent group selection allows a user to choose a constituent group and then choose a specific constituent from within that group. See About -> Learn More for a list of constituents.
Selecting a trend typeBased on the constituent selection, a user can choose from among the available trend types. Concentration is the amount of the constituent in the stream. Load is the mass of the constituent transported past the sampling point in a stream during a period of time. A metric is an index calculated to represent a specific characteristic of aquatic communities. Changes over time in water-quality concentration and load and changes in aquatic ecology-metrics can be strongly influenced by random and systematic variations in streamflow. Flow normalization removes the variation in concentration, load, or metric that is due to variations in streamflow. As a result, concentration and load trends are flow normalized and aquatic ecology metric trends are flow normalized. See FAQ #18 for more information. Note not all trend types are available for every constituent.
Selecting a trend periodBased on the constituent selection, a user can choose from among the available trend periods. Once the constituent, trend type, and trend period have been selected, the map will automatically update. Note not all trend periods are available for every constituent.