Why Budget for Water?

We might all understand why it's important to carefully budget our dollars, but budgeting water wisely is important too, according to a new report from the U.S. Geological Survey (USGS).

Understanding how the water cycle works and creating an accurate accounting -- a budget -- of how water moves through that cycle is critical for ensuring sustainable water supplies into the future, according to the USGS. The agency created its new report, "Water Budgets: Foundations for Effective Water-Resources and Environmental Management," to help natural resource professionals, government decision-makers and citizens better understand the need for water budgets.

The agency's goal is to "promote the wise use and management of a most precious resource -- water," said Robert M. Hirsch, chief hydrologist for the USGS.

Many factors affect the natural water cycle: geology, soils, vegetation, climate and land use. Humans can impact how water evaporates, runs off or replenishes aquifers with everything from farm drainage and irrigation systems to buildings, roads, parking lots and dams.

The USGS report examines several regions, including the High Plains, the Appalachicola River and the Chicago metropolitan area, to illustrate the value of water budgets. It also discusses a range of uncertainties to underscore how difficult it is to evaluate just how much water is available for people and the environment in general.

"While theoretically simple, water budgets, in practice, are often difficult to determine," the "Water Budgets" report states. "Balancing the water needs of humans with those of the many ecosystems on Earth will continue to be a challenge. Water budgets provide a means for evaluating the availability and sustainability of a water supply."

In the U.S., for example, people consume about 345 billion gallons of water -- about 40 bathtubs' full per person -- every day. Nearly half of that water is used by power plants that generate electricity, mostly for cooling and generating steam. Other sectors that use up large quantities of water include agriculture, industry, mining and livestock.

"The resource gained when humans import water to one location is accompanied by a loss of water at another location," the USGS report concludes. "In terms of water amounts, every gain is balanced by an equal loss. In terms of economic, cultural, and ecological values, the question of whether gains balance losses must be evaluated by society as a whole. Perhaps the greatest challenge to maintaining a sustainable future for our water resources is the development of policies and laws that balance the many water needs of humans with the water needs of their environment. Water budgets form a foundation upon which those policies and laws can be developed."

U.S. Geological Survey, "USGS Examines Importance of Water Budgets in Addressing Water Availability Concerns." URL: (http://www.usgs.gov/newsroom/article.asp?ID=1821)