Dos Osos Reservoir Replacement Project

Dos-Osos-Res-ReplacementEBMUD plans to replace its existing 0.24-million-gallon (MG) Dos Osos Reservoir with two 0.12 MG steel-bolted reservoirs. Located at 8 Los Norrabos in Orinda, the Dos Osos Reservoir was built in 1955 and has reached the end of its useful life. The reservoir will be replaced with smaller dual reservoirs, 70 feet higher in elevation, on EBMUD-owned watershed lands adjacent to the existing reservoir site. The higher elevation of the new dual reservoirs will increase water pressure and improve water service. Replacing the existing single reservoir with new dual reservoirs will also improve operational flexibility and water quality control.

The project will include construction of an approximately 12-foot wide, 800-foot long access road connecting Los Norrabos roadway to the new reservoir site, and a new 12-inch inlet-outlet pipeline installed in the new access road that will connect the new dual reservoirs to the existing water distribution system.

EBMUD’s existing Dos Osos Pumping Plant, located at 263 El Toyonal, Orinda, is a 0.3-million-gallons-per-day (MGD) pumping plant that will be rehabilitated as part of this project. The Dos Osos Pumping Plant will be upgraded with pump units that can supply the new dual Dos Osos Reservoirs.

Upon construction completion and successful testing of the new facilities, the existing Dos Osos Reservoir will be demolished. The project will replace existing aging infrastructure, improve level of service and increase operational flexibility. 

In accordance with the California Environmental Quality Act (CEQA), EBMUD completed a Mitigated Negative Declaration (MND) and determined that, with mitigation, this project will not generate significant impacts. The MND was released for a 31-day public review period from May 19, 2017 through June 19, 2017. All comments received on the MND have been compiled and responded to in the Final MND including any changes and clarifications to the MND. A copy of the Final MND is available for public review at the locations listed below or by download via the links at the bottom of this page.

EBMUD’s Administration Offices
375 11th Street
Oakland, CA 94607

Orinda Library
26 Orinda Way
Orinda, CA 94563


The EBMUD Board of Directors certified the Dos Osos Reservoir Replacement Project MND and approved the project, on October 10, 2017 at the regularly scheduled meeting in the Board Room at EBMUD Administration Offices, 375 Eleventh Street, Oakland, CA 94607. The proposed timeline for construction of this project is 2024-2025.


Kathryn Horn, Community Affairs Representative
Phone: 510-287-2053

Contractors: For bid opportunities please see the Business Center