U.S. Geological Survey Integrated Water Availability Assessment—2010–20, Chapter A

This is one chapter in a multichapter report that assesses water availability in the United States for water years 2010–20. This work was conducted as part of the fulfillment of the mandates of Subtitle F of the Omnibus Public Land Management Act of 2009 (Public Law 111-11), also known as the SECURE Water Act. As such, this work examines the spatial and
temporal distribution of water quantity and quality in surface water and groundwater, as related to human and ecosystem needs and as affected by human and natural influences.

Chapter A (this chapter) introduces the National Integrated Water Availability Assessment and provides important background and definitions for how the report characterizes water availability and its components. Chapter A also presents the key findings of Chapters B–F and thus acts as a summary of the entire report.

Chapter B (Gorski and others, 2025) is a national assessment of water supply, which is the quantity of water supplied through climatic inputs.

Chapter C (Erickson and others, 2025) is a national assessment of water quality, which is the chemical and physical characteristics of water.

Chapter D (Medalie and others, 2025) assesses water use including withdrawals and consumptive use in the conterminous United States.

Chapter E (Scholl and others, 2025) presents an analysis of factors affecting future water availability under changing climate conditions.

The National Integrated Water Availability Assessment culminates with Chapter F (Stets and others, 2025a), which is an integrated assessment of water availability that considers the amount and quality of water coupled with the suitability of that water for specific uses. Together, these six chapters constitute the National Integrated Water Availability Assessment for water years 2010–20.