According to a DOI release, as competition for water grows -- for irrigation of crops, for use by cities and communities, for energy production, and for the environment -- the need for the National Water Census and related information and tools to aid water resource managers also grows. The Water Census will assist water and resource managers in understanding and quantifying water supply and demand, and will support more sustainable management of water resources. Anne Castle, DOI's Assistant Secretary for Water and Science said, "It's true in other fields and no less so for water: you can't manage what you don't measure. The Water Census will quantify water supply and demand consistently across the entire country, fill in gaps in existing data, and make that information available to anyone who needs it -- and that represents a huge step forward on the path toward water sustainability."
The report -- Progress Toward Establishing a National Assessment of Water Availability and Use -- describes the "water budget" approach being taken to assess water availability for the nation. Water budgets account for the inputs to, outputs from, and changes in the amount of water in the various components of the water cycle. They are the hydrologic equivalent of the deposits to, withdrawals from, and changes in the balance in a checking account and provide the hydrologic foundation for analysis of water availability.
USGS is initially focusing production of the Water Census on areas with significant competition for water availability and existing or emerging conflicts over water supply, such as the Delaware, Colorado, and Apalachicola-Chattahoochee-Flint River Basins. Increasing populations, more volatile stream flows, energy development and municipal demands, and the uncertain effects of a changing climate amplify the need for an improved understanding of water use and water availability in these crucial watersheds. The Water Census (like our national population Census) is an ongoing effort that will provide information for current and future decision makers. USGS will continually be updating it, adding to it, and improving the accuracy of the various water budget components.
DOI said the Water Census is a component of the Department's WaterSMART initiative (Sustain and Manage America's Resources for Tomorrow), and fulfills a requirement under the Secure Water Act, part of the Omnibus Public Lands Management Act of 2009. Through WaterSMART, the Department is working to secure and stretch water supplies for use by existing and future generations to benefit people, the economy, and the environment, and to identify adaptive measures needed to address climate change and future demands.
The Omnibus Public Land Management Act of 2009 (Public Law 111-11) was passed into law on March 30, 2009. Subtitle F, also known as the SECURE Water Act, calls for the establishment of a "national water availability and use assessment program" within the U.S. Geological Survey (USGS). A major driver for this recommendation was that national water availability and use have not been comprehensively assessed since 1978. The report fulfills a requirement to report to Congress on progress in implementing the national water availability and use assessment program -- i.e. the National Water Census. The SECURE Water Act authorized $20 million for each of fiscal years (FY) 2009 through 2023 for assessment of national water availability and use. The first appropriation for this effort was $4 million in FY 2011, followed by an appropriation of $6 million in FY 2012.