February 23, 2006

Ms. Marguerite Naillon, Project Manager

Contra Costa Water District

P. O. Box H20

Concord, CA 94524-2099

Fax: (925) 686-2187

RE: Los Vaqueros Reservoir Expansion Project

Dear Ms. Naillon:

Thank you for this opportunity to comment on the Notice of Preparation of the Environmental Impact Report for the Los Vaqueros Reservoir Expansion Project. On behalf of the Board of Directors and members of the Mt. Diablo Audubon Society (MDAS), I would like to express a few of our serious concerns regarding the environmental impacts of the proposed expansion.

We support the need to protect native fisheries and to provide a reliable supply of high-quality drinking water for Contra Costa Water District’s customers. However, we believe that the proposed reservoir expansion and new ancillary facilities will have significant environmental impacts which cannot be adequately mitigated.

If the reservoir is expanded up to a 500,000-acre-foot facility, nearly 2,000 acres of grassland, oak woodland and wetlands will be inundated. These plant communities provide habitat for a number of special-status species, such as the San Joaquin kit fox, Alameda whipsnake, California tiger salamander, California red-legged frog, Golden eagle and other raptors. Portions of the area to be inundated are protected from such an incompatible use by perpetual conservation easements, which were required to mitigate for the environmental impacts of the initial reservoir project. To the best of our knowledge, there is no legal precedent for “breaking” these conservation easements, and we would oppose their extinguishment. Flooding these areas would also disrupt important wildlife corridors which allow seasonal movement and connect core reserves vital for foraging and reproduction. We are also concerned about the broader temporal disruption and impacts to species and habitat caused by construction of the various pipelines and other facilities contemplated by this project.

Los Vaqueros Reservoir Expansion

February 23, 2006

Page 2

An overriding issue for MDAS is the regional impact of the placement of an even larger body of water in an area which was formerly grassland and oak woodland. New species such as Bald eagle, Osprey and various gull species are now being seen at the reservoir. We suspect that these and other new residents may have impacts on endemic species, and we anticipate that a larger reservoir would exacerbate these impacts.

Mt. Diablo Audubon Society is very interested in following the progress of the proposed reservoir expansion. Please add MDAS to your mailing list for all future documents and notices for public meetings concerning this issue. In order to expedite the information, please use the following address:

Mt. Diablo Audubon Society

Conservation Committee

1091 Walker Avenue

Walnut Creek, CA 94596

Thank you for your consideration in this matter.

Sincerely,

Michael R. Williams

President

Cc: Ms. Patricia Roberson, Project Manager

Bureau of Reclamation

2800 Cottage Way

Sacramento, CA 95825-1898

Fax: (916) 978-5094

Seth Adams

Save Mt. Diablo

1901 Olympic Blvd., Suite 220

Walnut Creek, CA 94596

Fax: (925) 947-0642