Integrated Water Availability Assessments (IWAAs)

Science Center Objects

The USGS Integrated Water Availability Assessments (IWAAs) are a multi-extent, stakeholder driven, near real-time census and seasonal prediction of water availability for both human and ecological uses at regional and national extents.

The USGS Integrated Water Availability Assessments (IWAAs) combine resources and knowledge gained from previous and ongoing USGS efforts such as Focus Area Studies, Regional Groundwater Availability Studies, Water Use estimation, Ecological Water Needs, and Streamflow estimation, in addition to utilizing and providing feedback to the National Water Model. The IWAAs are designed to provide information to meet the goals of the National Water Census as established through the SECURE Water Act. These goals are to:

  1. Provide accurate assessment of available water resources
  2. Determine quantity of water available for human and ecological needs
  3. Quantify long-term trends in water availability
  4. Provide assessment of change in water availability
  5. Explore factors that limit water availability or could lead to conflict
  6. Forecast water availability for economic development, energy production or conservation, and environmental or other in-stream uses

When fully implemented, the IWAAs will:

  1. Evaluate current water supply and demand
  2. Evaluate long-term trends in water availability
  3. Provide seasonal to decadal forecasts of availability
  4. Inform water resource decisions through development of socioeconomic tools


IWAAs will build upon concepts learned from the Mississippi Alluvial Plain (MAP) project to produce the data, tools, and information water resource managers need to make management decisions. The MAP focuses on quantifying the status of the groundwater system and determining how groundwater resources respond to development.

In FY 2019, the Water Availability and Use Science Program selected 10 projects across the U.S. that will help to support development of National and Regional IWAAs. These projects will be conducted with State and local partners with the support of Cooperative Matching Funds.


Diagram showing the Integrated Water Availability Assessment process

Diagram showing the Integrated Water Availability Assessment process.

REGIONAL IWAAs will build on and help advance a NATIONAL IWAA synthesis.

The regional, or basin-scale IWAAs are designed to simulate each component within specific basins that are selected based on multiple metrics to determine greatest need first. Regional IWAAs build upon past regional groundwater availability studies and focus area studies, as well as other program activities within the Water Availability and Use Science Program (WAUSP),  Groundwater and Streamflow Information Program (GWSIP), and the National Water Quality Program (NWQP). Each regional IWAA is designed to utilize and provide feedback on the types of monitored information within a selected basin. The regional IWAAs are ideally implemented in concert with Next Generation Water Observing Systems (NGWOS) that may gather information such as streamflow, soil moisture, precipitation, temperature, etc. The information gained from monitoring are used as observations in the IWAAs simulation, and the simulation can provide 'worth' of the existing data or potential new data collection sites. A regional IWAA may simulate process such as stream flow, groundwater flow, and water quality with regard to climatic conditions and water use. The amount of water available in the regional IWAA may be constrained by water required for ecologic use, drought, quality, impacts on infrastructure, and economics. Each of these constraints may vary by region, thus the regional IWAAs require a great deal of local stakeholder input.

The National IWAA assimilates the components above at nationally available scales and data and information gained from regional IWAAs. The National IWAA is designed to provide periodic snapshots of water availability across the U.S. based on regional constraints in an evolving simulation as more regional IWAAs are completed and inform the National IWAA.

Illustration showing national Integrated Water Availability Assessments (IWAA) components

Illustration showing national Integrated Water Availability Assessments (IWAAs) components.