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Filling the Biggest Data Gap in Water Management

About OpenET

Sustainable water management is one of the most challenging issues of our time, especially in the arid western U.S. Adequate water supplies are crucial to maintaining the health of communities, rivers, and wildlife, and nothing is more important to agriculture’s ability to produce food for the world’s growing population. Maximizing the benefits of our water supplies requires careful measurement of their availability and use. For irrigated agriculture, satellite-based estimates of evapotranspiration (ET) provide a measure of the water used to grow food — the biggest share of water consumption in most arid environments around the world. However, access to this data has been limited and expensive, keeping it out of the hands of most water users and decision-makers.

OpenET aims to provide open, easily accessible satellite-based ET data for improved water management.

The project team includes leading national and international experts in remote sensing of ET, cloud computing, water policy, and water markets, partnered with nationally recognized web development teams and leaders in the western agriculture and water management communities. Development of OpenET is supported by the S.D. Bechtel, Jr. Foundation; the Gordon and Betty Moore Foundation; the Walton Family Foundation; the Windward Fund; the Water Funder Initiative; and the NASA Applied Science Program. In-kind support is provided by Google Earth Engine.


When evaluating evapotranspiration rates from crops on irrigated land, it is crucial to consider the many factors that may lead to variations across fields and regions, even within the same crop type. These include soil type and salinity, ground cover and/or the need to irrigate a cover crop, the age of an orchard or vineyard, irrigation system type, groundwater recharge efforts, production goals, pest and pathogen management considerations, and other factors.

Also, please note that data provided by OpenET throughout this year is provisional and will be revised once the OpenET team has completed its intercomparison and accuracy assessment effort. Until the intercomparison is complete, and the data has been thoroughly reviewed and received final approval, users are cautioned to consider carefully the provisional nature of the information before using it for decision-making purposes with any real or significant consequences. We kindly ask that these numbers remain private, and are not to be shared beyond the internal partner release without prior approval from the OpenET team.

For additional questions about the accuracy and appropriate uses of this ET data, please contact Robyn Grimm, Environmental Defense Fund, at rgrimm@edf.org.

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