Integrated Water Availability Assessments Fundamentals
USGS releases a comprehensive look at water resources in the United States
New National Water Availability Assessment offers critical insights into water supply, demand, and quality across the Nation.
Water Priorities for the Nation: IWAAs
Factsheet outlines the goals and deliverables of the Integrated Water Availability Assessments Program
The USGS Water Resources Mission Area is assessing how much water is available for human and ecological needs in the United States and identifying where and when the Nation may have challenges meeting its demand for water.
National Water Availability Assessment
The USGS National Water Availability Assessment consists of reports, which provide a scientific summary and interpretation of water quantity, quality and use, and the data companion, which delivers model-based estimates of water supply and demand.
Integrated Water Availability Assessments produced by the USGS Water Resources Mission Area (WMA) will provide estimates of water supply and demand in the past, present, and future. These assessments, or studies with an emphasis on quantifying and understanding water availability, will investigate historical changes in water supply and demand and their causes, and help us identify where and when the Nation may have challenges meeting its demand for water because of insufficient water quantity or quality. Understanding water supply and demand will support better and more efficient water management for economic growth, protection of aquatic ecosystems, agriculture and energy production, and human population growth. These assessments will also support adaptive management in areas of emerging imbalance between water supply and demand.
What is the Water Resources Mission Area producing as part of its water availability assessments?
We have identified three high-priority outcomes, or products, for our water availability assessments:
PRODUCT | DESCRIPTION | OBJECTIVES |
Scientific assessments of water availability in the United States, completed every five years |
| |
Regularly updated online information on water availability in the United States |
| |
One-time scientific assessments of water availability in different hydrologic regions across the United States |
|

These three products are designed to be interdependent:
- Models underpinning the National Water Availability Assessment Data Companion (NWDC) will be used for interpretation in the National Water Availability Assessment reports.
- Activities in each Regional Water Availability Assessment will help fill gaps in national models, improving future versions of the National Water Availability Assessment Data Companion (NWDC).
- Activities in the Regional Water Availability Assessments will also provide detailed and variable case studies to help explain national patterns identified in the National Water Availability Assessment reports.
The USGS Integrated Water Availability Assessments Program is coordinating the delivery of these three products.
National Water Availability Assessments
The National Water Availability Assessments will provide the synthesis and interpretation of water availability in the past, present, and future. These assessments will be modeled in part after the previous national assessments conducted by the Water Resources Council in the 1960s and 1970s. They will also build on more recent reporting by the USGS on national water use and water quality conducted through the WMA’s Water Availability and Use Program and the former National Water Quality Assessment (NAWQA) program. These new assessments will include more model predictions, allowing us to fill in spatial and temporal gaps in our monitoring records; evaluate water quantity, quality, and use at the same time; and make forecasts into the future.
The National Water Availability Assessments will also provide insights into regional and topical aspects of water availability. For example, the National Water Availability Assessments may use results from the Regional Water Availability Assessments to better understand the behavior of individual water-availability components and help explain broader regional and national patterns. The National Water Availability Assessment reports may also consider topical issues that cut across multiple components of water availability, such as wildfire and its effects on water quantity, quality, and use.
Because of the large scope of the National Water Availability Assessments, they will be produced on a five-year cycle to allow enough time for generation of new information, synthesis, interpretation, review, and publication. Additional products that are smaller in scope, like data visualizations, short topical summaries, and journal articles, will be released in the years between the national assessments.
National Water Availability Assessment Data Companion
The National Water Availability Assessment Data Companion (NWDC) will provide regularly updated online information about water quantity, quality, and use of the Nation’s surface and groundwater. The information in the National Water Availability Assessment Data Companion (NWDC) will cover past conditions over multiple decades as well as future projections over multiple decades. This centralized delivery of model and trend information will complement the centralized delivery of observational data in USGS Water Data for the Nation (WDFN).
The National Water Availability Assessment Data Companion (NWDC) will allow people outside USGS to use webservices and APIs to pull data and model predictions into their own models, map viewers, and other tools. It also will allow users to interactively visualize and explore the data online through mappers and dashboards.
Regional Water Availability Assessments

Regional Water Availability Assessments will be conducted in medium-sized watersheds that are representative of larger regions throughout the Nation. These assessments are designed to capture a range of conditions in major drivers of water availability. Some regional water availability assessments occur in Integrated Water Science Basins, which represent a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources. Models, tools, and supporting data developed for the National Water Availability Assessment Data Companion and National Water Availability Assessments will provide a starting point for the Regional Water Availability Assessments. In turn, the regions will provide a test bed for innovative methods and approaches in data collection, trend analysis, research, model development, and assessment of water availability. These innovations will be designed to inform the Regional Water Availability Assessments and improve the accuracy of national models and assessments.
The Regional Water Availability Assessments have two main tasks:
TASK | DESCRIPTION |
Focused assessment of regionally relevant threats to water availability |
|
Base evaluation of regional water supply and demand |
|
Below are other USGS science efforts related to Integrated Water Availability Assessments.
Monthly inorganic nitrogen atmospheric wet deposition estimates for the conterminous United States, 1999 through 2020
Annual Nutrient Loads at Illinois EPA Ambient Water Quality Monitoring Network Sites, Water Years 1976–2021
PRMS simulator used to assess rainfall, runoff, and river flow for the National Hydrologic Model (NHM) Puerto Rico
Monthly estimates of natural baseflow for 15,866 stream reaches, defined by the National Hydrography Dataset Plus Version 2.0 (NHDPlusV2), in the Delaware River Basin for the period 1950-2015
Water-quality and streamflow datasets used in Weighted Regressions on Time, Discharge, and Season (WRTDS) models to determine trends in the Nation’s rivers and streams, 1972-2017
Water-quality trends for rivers and streams in the Delaware River Basin using Weighted Regressions on Time, Discharge, and Season (WRTDS) models, Seasonal Kendall Trend (SKT) tests, and multisource data, Water Year 1978-2018
Daily-timestep and monthly-timestep estimates of baseflow at 49 reference stream gages located within 25 miles of the Delaware River basin watershed boundary for the years 1950 through 2015
Annual low flow, climate and watershed properties for 325 USGS gages in and near the Delaware River Basin
Multi-source surface-water-quality data and U.S. Geological Survey streamgage match for the Delaware River Basin
Below are publications associated with Integrated Water Availability Assessments.
Water priorities for the Nation—U.S. Geological Survey Integrated Water Availability Assessments
Below are data or web applications associated with Integrated Water Availability Assessments.
The USGS Water Resources Mission Area is assessing how much water is available for human and ecological needs in the United States and identifying where and when the Nation may have challenges meeting its demand for water.
National Water Availability Assessment
The USGS National Water Availability Assessment consists of reports, which provide a scientific summary and interpretation of water quantity, quality and use, and the data companion, which delivers model-based estimates of water supply and demand.
Integrated Water Availability Assessments produced by the USGS Water Resources Mission Area (WMA) will provide estimates of water supply and demand in the past, present, and future. These assessments, or studies with an emphasis on quantifying and understanding water availability, will investigate historical changes in water supply and demand and their causes, and help us identify where and when the Nation may have challenges meeting its demand for water because of insufficient water quantity or quality. Understanding water supply and demand will support better and more efficient water management for economic growth, protection of aquatic ecosystems, agriculture and energy production, and human population growth. These assessments will also support adaptive management in areas of emerging imbalance between water supply and demand.
What is the Water Resources Mission Area producing as part of its water availability assessments?
We have identified three high-priority outcomes, or products, for our water availability assessments:
PRODUCT | DESCRIPTION | OBJECTIVES |
Scientific assessments of water availability in the United States, completed every five years |
| |
Regularly updated online information on water availability in the United States |
| |
One-time scientific assessments of water availability in different hydrologic regions across the United States |
|

These three products are designed to be interdependent:
- Models underpinning the National Water Availability Assessment Data Companion (NWDC) will be used for interpretation in the National Water Availability Assessment reports.
- Activities in each Regional Water Availability Assessment will help fill gaps in national models, improving future versions of the National Water Availability Assessment Data Companion (NWDC).
- Activities in the Regional Water Availability Assessments will also provide detailed and variable case studies to help explain national patterns identified in the National Water Availability Assessment reports.
The USGS Integrated Water Availability Assessments Program is coordinating the delivery of these three products.
National Water Availability Assessments
The National Water Availability Assessments will provide the synthesis and interpretation of water availability in the past, present, and future. These assessments will be modeled in part after the previous national assessments conducted by the Water Resources Council in the 1960s and 1970s. They will also build on more recent reporting by the USGS on national water use and water quality conducted through the WMA’s Water Availability and Use Program and the former National Water Quality Assessment (NAWQA) program. These new assessments will include more model predictions, allowing us to fill in spatial and temporal gaps in our monitoring records; evaluate water quantity, quality, and use at the same time; and make forecasts into the future.
The National Water Availability Assessments will also provide insights into regional and topical aspects of water availability. For example, the National Water Availability Assessments may use results from the Regional Water Availability Assessments to better understand the behavior of individual water-availability components and help explain broader regional and national patterns. The National Water Availability Assessment reports may also consider topical issues that cut across multiple components of water availability, such as wildfire and its effects on water quantity, quality, and use.
Because of the large scope of the National Water Availability Assessments, they will be produced on a five-year cycle to allow enough time for generation of new information, synthesis, interpretation, review, and publication. Additional products that are smaller in scope, like data visualizations, short topical summaries, and journal articles, will be released in the years between the national assessments.
National Water Availability Assessment Data Companion
The National Water Availability Assessment Data Companion (NWDC) will provide regularly updated online information about water quantity, quality, and use of the Nation’s surface and groundwater. The information in the National Water Availability Assessment Data Companion (NWDC) will cover past conditions over multiple decades as well as future projections over multiple decades. This centralized delivery of model and trend information will complement the centralized delivery of observational data in USGS Water Data for the Nation (WDFN).
The National Water Availability Assessment Data Companion (NWDC) will allow people outside USGS to use webservices and APIs to pull data and model predictions into their own models, map viewers, and other tools. It also will allow users to interactively visualize and explore the data online through mappers and dashboards.
Regional Water Availability Assessments

Regional Water Availability Assessments will be conducted in medium-sized watersheds that are representative of larger regions throughout the Nation. These assessments are designed to capture a range of conditions in major drivers of water availability. Some regional water availability assessments occur in Integrated Water Science Basins, which represent a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources. Models, tools, and supporting data developed for the National Water Availability Assessment Data Companion and National Water Availability Assessments will provide a starting point for the Regional Water Availability Assessments. In turn, the regions will provide a test bed for innovative methods and approaches in data collection, trend analysis, research, model development, and assessment of water availability. These innovations will be designed to inform the Regional Water Availability Assessments and improve the accuracy of national models and assessments.
The Regional Water Availability Assessments have two main tasks:
TASK | DESCRIPTION |
Focused assessment of regionally relevant threats to water availability |
|
Base evaluation of regional water supply and demand |
|
Below are other USGS science efforts related to Integrated Water Availability Assessments.
Monthly inorganic nitrogen atmospheric wet deposition estimates for the conterminous United States, 1999 through 2020
Annual Nutrient Loads at Illinois EPA Ambient Water Quality Monitoring Network Sites, Water Years 1976–2021
PRMS simulator used to assess rainfall, runoff, and river flow for the National Hydrologic Model (NHM) Puerto Rico
Monthly estimates of natural baseflow for 15,866 stream reaches, defined by the National Hydrography Dataset Plus Version 2.0 (NHDPlusV2), in the Delaware River Basin for the period 1950-2015
Water-quality and streamflow datasets used in Weighted Regressions on Time, Discharge, and Season (WRTDS) models to determine trends in the Nation’s rivers and streams, 1972-2017
Water-quality trends for rivers and streams in the Delaware River Basin using Weighted Regressions on Time, Discharge, and Season (WRTDS) models, Seasonal Kendall Trend (SKT) tests, and multisource data, Water Year 1978-2018
Daily-timestep and monthly-timestep estimates of baseflow at 49 reference stream gages located within 25 miles of the Delaware River basin watershed boundary for the years 1950 through 2015
Annual low flow, climate and watershed properties for 325 USGS gages in and near the Delaware River Basin
Multi-source surface-water-quality data and U.S. Geological Survey streamgage match for the Delaware River Basin
Below are publications associated with Integrated Water Availability Assessments.
Water priorities for the Nation—U.S. Geological Survey Integrated Water Availability Assessments
Below are data or web applications associated with Integrated Water Availability Assessments.