Photo: Doug Chalmers / SEI

Since 2017, SEI has been assisting the California State Water Resources Control Board with implementation of the California Water Action Plan . A goal of the plan is the restoration of important species and habitat. To that end, SEI is providing expertise in water rights analysis, water allocation modelling, ecosystem impacts, and decision support for efforts in the South Fork Eel, Shasta and Ventura River watersheds.

SEI staff have worked with the state’s water rights database, eWRIMS, to develop the eWRIMS Analyzer tool for rapidly assessing the legally defined water uses in a basin. The eWRIMS Analyzer can identify common data discrepancies, catalog beneficial uses, estimate the monthly legal maximum water use and estimate the monthly reported water use. SEI has also worked with Water Board staff to estimate illegal cannabis diversions in the South Fork Eel watershed.

With the water use information developed using eWRIMS and other sources, SEI is building the South Fork Eel River Water Allocation Model (SEWAM) using SEI’s WEAP software. WEAP is ideally suited to studying the impact of in-stream flow requirements on agriculture, rural communities, aquatic habitat and other beneficial uses in a watershed. In the development of the model, every water right is explicitly represented, allowing for a detailed assessment of the impact of in-stream flow requirements on water availability for all water users in a basin.

Working with partners at the Water Board, California Department of Fish and Wildlife , UC Davis , and Utah State University, SEI is participating in the development of a framework for assessing ecosystem needs, developing in-stream flow regimes, and testing them in the water allocation models to determine impacts on other water users. With these models, the information is generated to quantify the trade-offs inherent in allocation of limited water supplies.

Finally, SEI, UC Davis, and Utah State University are providing Board staff with state-of-the-art visualization techniques to explore the trade-offs between in-stream flows and other water uses. Using the Tableau software, the team is developing graphics that help decision-makers understand the spatial nature of the problem, analyze it for different climate conditions, and assess the impacts of in-stream flow regimes under a range of uncertainty in legal and illegal water use and management.