In the American West, where precipitation is scarce and agriculture is a major industry, water management is a big deal. Trying to track who uses water and where has been expensive and difficult. Most monitoring now is done at the county level by monitoring flow in irrigation canals or by monitoring electrical use at individual wells. That's one reason why Idaho developed a tool that — at greater detail and lower cost than previous methods — measures water usage in the state. The tool, Mapping EvapoTranspiration at high Resolution with Internalized Calibration, or METRIC, uses surface-temperature readings from government satellites, air temperature and a system of algorithms to measure how much water is lost through evaporation and transpiration, the release of water vapor by plants. In Idaho, irrigated agriculture accounts for more than 90 percent of water use in the state. By tracking usage on a field-by-field basis, the state can more effectively understand and regulate water use. Water resource managers in Idaho and other states see the method as the best way to help settle growing regional disputes over water supplies. In addition, Idaho has used the data collected to help planners evaluate the impact of population growth, protect salmon and steelhead habitats and monitor ground water pumped out of aquifers for irrigation wells. Launched in 2000, METRIC, developed by the state Department of Water Resources and the University of Idaho, is in use in 11 states. It is one of six programs out of 700 entries nationwide to win a 2009 Innovations in American Government Award.