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Sacramento River in California cuts through green tree-covered grassland at sunset.

A new SEI tool sheds light on one of the world’s most complicated water systems

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A new SEI tool sheds light on one of the world’s most complicated water systems

The eWRIMS Analyzer transforms California’s water rights data into accessible reports on monthly water use in each watershed.

Emily Yehle / Published on 18 August 2021

California policymakers are now able to model reported water use easily and quickly in any basin in the state thanks to a new SEI tool.

The tool, developed for the California State Water Resources Control Board, captures data from the Electronic Water Rights Information Management System (eWRIMS). It then analyses the data to provide users with a monthly water use estimate for every water right in any given watershed.

The tool, known as the eWRIMS Analyzer, also flags missing and erroneous data.

“This tool is unique in its comprehensiveness, pulling from multiple sources of data within eWRIMS to select the most reliable estimate for each water right,” said SEI Associate Scientist Doug Chalmers, who is developing the tool with colleagues in the SEI US Water Program. “The eWRIMS Analyzer recognizes common discrepancies in the database and provides a user-friendly interface to semi-automatically resolve them. This way, policymakers can gain a full picture of water use and any reporting issues in a watershed.”

The tool also may be useful in granting new water rights, including rising demand from cannabis operations. Every new water right requires the government to conduct an analysis on how much water is being diverted in a watershed and how much is available for new users. The eWRIMS Analyzer makes that process far easier.

Additionally, the tool can be used when determining requirements for in-stream flows, or water that flows in rivers. Policymakers can use the eWRIMS Analyzer to see how such ecosystem requirements will affect existing water use and to better weigh the trade-offs between ecosystem protections and urban and agricultural water use.

“Each watershed in California is unique: some are agricultural, with only a few large water users, while others are a complex network of small, individual water rights and permits,” said SEI Senior Scientist Charles A. Young. “By building customization options into the eWRIMS Analyzer, the tool can be used effectively across the whole diverse state of California.”


Doug Chalmers



Profile picture of Charles A. Young
Charles A. Young

Senior Scientist


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