Dam Assessment and Rehabilitation Projects


SCH Number
Public Agency
Metropolitan Water District of Southern California
Document Title
Dam Assessment and Rehabilitation Projects
Document Type
NOE - Notice of Exemption
Document Description
Metropolitan has a conveyance and distribution system that includes 26 dams and reservoirs that store treated and raw water, of which 21 are under the jurisdiction of the California Department of Safety of Dams (DSOD). As a responsible dam owner, Metropolitan regularly monitors and evaluates the performance of its dams. Consistent with industry practice, Metropolitan initiated the Dam Safety and Rehabilitation Program in 2004 to review the adequacy of Metropolitan's dams, evaluate risks, and identify alternative solutions to minimize risks. Metropolitan has authorized a Seismic Assessment Study to provide an overall evaluation of the seismic safety of Metropolitan's dams and appurtenant structures. This Seismic Assessment Study is being executed in four phases to provide a systematic, rational, and cost-effective assessment approach. Metropolitan has completed Phases 1 and 2 and determined that of the 26 dams, 11 dams would not be subject to seismic instability, and no further study or analysis is warranted. For the remaining 15 dams, additional specialized evaluations are recommended to assess their overall seismic safety. The assessment of 13 dams will be conducted under Phase 3 of the Seismic Assessment Study. The facilities to be assessed include Orange County, Live Oak, Palos Verdes, Garvey, Gene Wash, and Copper Basin reservoirs, the finished water reservoirs at Mills, Jensen, and Skinner treatment plants, Lake Mathews, and Lake Skinner. Several facilities have multiple dams at a single location. The remaining two dams are located at the Diemer Plant and are being evaluated under a separate captial program for that facility. Under the Phase 3 Study, additional information will be obtained through limited field and laboratory investigations, and simplified seismic analysis will be conducted. Visual observations of the existing riprap slope protection on the upstream face of the Owen Dam (West Dam) at Diamond Valley Lake has identified signs of shifting riprap under high wave/wind loads. While these conditions do not jeopardize the overall safety of the dam, if left unattended the riprap will continue to shift, causing recurring maintenance and repair problems. Metropolitan proposes to perform a study to determine the best method of repair to prevent shifting of the riprap.

Contact Information

Delaine W. Shane
Agency Name
Metropolitan Water District of Southern California
Contact Types
Lead/Public Agency


Los Angeles, Orange, Riverside, San Bernardino
Other Location Info
Various cities

Notice of Exemption

Exempt Status
Categorical Exemption
Type, Section or Code
Section 15301, 06, 09; 15378(b)(
Reasons for Exemption
Sections: 15378(b)(4) The proposed project consists of the operation, repair, maintenance, permitting, leasing, licensing, or minor alteration of existing public or private structures, facilities, mechanical equipment, or topographic features, involving negligible or no expansion of use beyond that existing at the time of the lead agency's determination. The proposed project consists of basic data collection, research, experimental management, and resource evaluation activities, which do not result in a serious or major disturbance to an environmental resource. These may be strictly for information gathering purposes, or as part of a study leading to an action, which a public agency has not yet approved, adopted or funded. The proposed project consists of activities limited entirely to inspections, to check for performance of an operation, or quality, health, or safety of a project, including related activities. The creation of government funding mechanisms or other government fiscal activities, which do not involve any commitment to any specific project, which may result in a potentially significant physical impact on the environment, are not subject to CEQA.

Disclaimer: The document was originally posted before CEQAnet had the capability to host attachments for the public. To obtain the original attachments for this document, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at state.clearinghouse@opr.ca.gov or via phone at (916) 445-0613.

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