Shasta River Water Allocation Model

The Shasta River is a tributary of the Klamath River located in Siskiyou County in far northern California to the north and east of Mount Shasta. The Shasta River watershed is important for both agriculture and aquatic habitat for migratory fish moving up the Klamath River. Since 2017, SEI has assisted the California State Water Resources Control Board with implementing the California Water Action Plan. A goal of the plan is to restore important species and habitat. To that end, SEI provides 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 is developing the Shasta River Water Allocation Model (ShaRWAM) to help evaluate potential management actions in the watershed related to the California Water Action Plan, 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 developing 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.

The model uses input hydrology from a Loading Simulation Program in C++ (LSPC) model constructed by Paradigm Environmental, remotely sensed derived crop demands from David’s Engineering, as well as detailed water right place of use and legal diversion limits from the 1932 Shasta River Adjudication and from California’s state water right database, eWRIMS. SEI used its eWRIMS Analyzer tool to extract water right allocation data and rapidly assess the legally defined water uses in the basin. The eWRIMS Analyzer identifies common data discrepancies, catalogs beneficial uses, and estimates the monthly legal and reported water use.