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California Water Plan Update

SEI has worked with the California Department of Water Resources since 2006 to inform updates to the California Water Plan, using SEI’s flagship water modelling tool, WEAP.

Active project


Project contact

Brian Joyce /

Aerial view of meandering river surrounded by tributary streams and green vegetation

Photo: Artur Debat / Getty Images

The California Water Plan (CWP) provides a framework for water managers, legislators and the public to consider options and make decisions about California’s water future. The Plan presents information on California’s water resources, including water supply evaluations and assessments of various water uses to quantify gaps between water supplies and demands. The Plan identifies and evaluates existing and proposed methods to manage water demand and boost supply to address California’s water needs. The Plan is updated every five years to keep pace with changes occurring across the state.

Since 2006, SEI has worked with the California Department of Water Resources to develop an application of the Water Evaluation and Planning (WEAP) model that serves as the analytical foundation for the California Water Plan Update process. The WEAP application simulates integrated water management scenarios for six of the 10 hydrologic regions in California. This application includes a representation of the source watersheds in the Central Valley water system, the major hydraulic infrastructure, the Sacramento–San Joaquin Delta operating constraints, and more than 85% of the state’s agricultural and domestic water use.

This application – developed by SEI – is used to conduct integrated scenarios analysis, wherein various management strategies are assessed within a range of uncertainty relating to future trends in water demand and climate.

This analysis includes:

  • quantifying a small set of handcrafted narrative scenarios developed by the CWP Update staff and advisory committee; and
  • generating a larger ensemble of plausible scenarios to systematically evaluate the performance of various regional water management response plans in the face of a number of critical uncertainties, including climate change.

Project team

Profile picture of Brian Joyce
Brian Joyce

Senior Scientist


Profile picture of Charles A. Young
Charles A. Young

Senior Scientist


Profile picture of Jack Sieber
Jack Sieber

Senior Scientist


Design and development by Soapbox.