Los Vaqueros Reservoir Expansion Project

The expansion of Los Vaqueros Reservoir is an important component of improving regional water supply resiliency and emergency preparedness, promoting multi-agency partnerships and providing recreational and environmental benefits.


The expansion will protect the Bay Area’s drinking water quality and reliability, reduce effects of delta water diversions on aquatic resources and enhance the Delta environment, and improve recreation and habitat resources in the reservoir watershed.

Marguerite Patil
Special Assistant to the General Manager and
Project Manager for Los Vaqueros
Why does this project matter?

The goal of this two-phase expansion project is to protect the Bay Area’s drinking water quality and reliability, enhance emergency water storage, reduce effects of Delta water diversions on aquatic resources, improve recreation and habitat resources in the reservoir watershed, and provide much-needed water for wildlife refuges.

What is ESA doing to help?

ESA has provided comprehensive environmental planning and compliance services for both expansion project phases. This includes leading the project definition, alternatives development and screening, environmental studies, public outreach, CEQA and NEPA documentation, and permitting, all of which require extensive interagency cooperation.

As part of the comprehensive environmental permitting and EIS/EIR processes, we have participated in an extensive outreach program with the general public, key stakeholders, and regulatory agencies.

The Phase 1 reservoir expansion project, completed in 2012, increased the existing reservoir from 100,000 acre-feet to 160,000 acre-feet. During this phase, we helped Contra Costa Water District identify and evaluate more than 3,000 acres of land for acquisition and enhancement to meet mitigation and permit compensation requirements for affected habitats and sensitive species. We also provided field monitoring and compliance services during construction.

The Phase 2 expansion, targeting final design by 2021, proposes to increase the reservoir to 275,000 acre-feet with multi-agency buy-in to provide regional benefits. For this phase of work, we are leading a supplemental CEQA/NEPA compliance and environmental permitting process as well as supporting recreational facility design.


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