From Reservoir To Riffle - A Multi-Model Approach To Assess Water Supply and Environmental Benefits of The Pacheco Reservoir Expansion Project

The Pacheco Reservoir Expansion Project is a multi-agency strategic and long-term investment to provide environmental benefits and ensure a more reliable supply of safe, clean drinking water in the face of climate change. The Project, located in Santa Clara County, California, would increase the storage capacity of the existing Pacheco Reservoir from 5,500 acre-feet to approximately 140,000 acre-feet through construction of a new dam, conveyance facilities, and appurtenant infrastructure. The expanded reservoir would be operated primarily to increase water supply reliability and system operational flexibility, and to increase suitable spawning and rearing habitat for South-Central California Coast steelhead in Pacheco Creek.

Evaluation of Project operations requires simulation of three major interrelated systems: (1) the statewide Central Valley Project and California State Water Project, (2) local water supply and distribution systems, and (3) the Pacheco Creek watershed, including the expanded reservoir, Pacheco Creek, and major tributaries. This talk will describe the multi-model framework developed to evaluate Project operations and assess water supply and environmental benefits. Emphasis will be placed on the development and simulation of reservoir release schedules, and how the modeling framework was applied to quantify water supply benefits and downstream flow, water temperature, and habitat benefits.