Title
Consider amending the Nacimiento Dam Operation Policy
Report
RECOMMENDATION:
It is recommended that the Monterey County Water Resources Agency Board of Directors:
Amend the Nacimiento Dam Operation Policy
SUMMARY/DISCUSSION:
The Nacimiento Dam Operation Policy Manual (Policy) was first adopted in 1996 and last amended on April 24, 2000. Beginning in 2010, significant changes in reservoir operations have been implemented as a result of the construction of the Salinas Valley Water Project (SVWP). This version of the Policy (Attachment 1) incorporates such changes, including a Nacimiento Dam rule curve change and reoperation of the Nacimiento Dam and Reservoir in accordance with the SVWP Biological Opinion and water rights license requirements. This Policy does not reflect new policy but rather consolidates all existing operational procedures, permits, and requirements into a single concise report.
The process to draft this Policy began in the fall of 2015 when the Reservoir Operations Advisory Committee recommended forming a subcommittee to update the operation policies for Nacimiento and San Antonio dams. The subcommittee was made up of eight members and held eight meetings from December 2015 to August 2017. During this period, Monterey County Water Resources Agency (Agency) staff received input from subcommittee members (Attachment 2). Staff carefully considered the comments received and sought advice from legal counsel regarding such comments. As a result, most of the comments received from the subcommittee were incorporated in the Policy with the exception of the following:
• Acknowledgement that water rights of Salinas Valley property owners are senior to Agency water rights. It should be noted that the purpose of the Policy is to guide the Agency in operating the Nacimiento Dam consistent with its water rights. In compliance with the Agency water rights, operations described in the Policy include the capture of water belonging to the Agency and releases of this water for permitted beneficial uses. This Policy is not intended to address the various water rights of downstream users.
• Inclusion of operational criteria to meet flow targets for enhancing steelhead migration identified in the Salinas Valley Water Project EIR in addition to the flow prescriptions for steelhead migration in the Biological Opinion. Language was added to the Policy to clarify that the addendum to the Final EIR/EIS adopted on July 30, 2007 specifically includes a description of the new flow prescriptions developed as part of the Biological Opinion that modified and superseded any previously identified flow regimes in the final EIR/EIS.
• Inclusion of a description of operations that would result in additional releases as referenced in the SVWP Engineer’s Report. Rather than addressing this subject in this Policy, a detailed description of releases will be part of a report to be prepared annually as stated in the Policy.
• Inclusion of a flood operations rule curve from the Salinas Valley Water Project EIR. The California Department of Water Resources, Division of Safety of Dams (DSOD) is responsible for issuing a Certificate of Approval showing the conditions under which the Agency can operate Nacimiento Dam. On December 29, 2009, the DSOD issued a Certificate of Approval to the Agency for the impoundment of water up to an elevation of 800 feet NGVD29, the top of the inflated spillway gate system. If the reservoir reaches an elevation of 801 feet, an operator shall be dispatched to the dam to ensure the gates are fully lowered. Keeping the safety of Nacimiento Dam as the highest priority, the Agency will identify a self - imposed range of operating elevations within the flood pool elevation 787.75 feet to elevation 800 feet) that will provide adequate reservoir storage space during the winter for the Agency to respond to forecasted storm events. This process has been described in the Flood Control operation section of the policy document.
• Consideration of keeping the Nacimiento Reservoir at a minimum recreation elevation above 750 feet until after Labor Day. The current goal is to keep the reservoir elevation above 730 feet until Labor Day. The current goal is a more realistic goal that has been historically achieved approximately 78% of the time during the first week of September during the sixty years Nacimiento Reservoir has been in operation.
This document is meant to be a living document and subject to revision due to future projects, changes in regulatory requirements, agreements with outside entities, or the need for changes in operational procedures. Revisions will be subject to approval by the Agency Board of Directors.
At its November 30, 2017 monthly meeting, the Reservoir Operations Advisory Committee recommended that the Agency Board of Directors consider amending the Nacimiento Dam Operation Policy. After this Policy is amended by the Board of Directors, staff is planning to update the Operation Policy Manual for San Antonio Dam.
OTHER AGENCY INVOLVEMENT:
San Luis Obispo County Flood Control and Water Conservation District had a representative in the Policy Subcommittee and provided comments.
FINANCING:
None.
Prepared by: Germán Criollo, Associate Water Resources Hydrologist, (831) 755-4860
Approved by ___________________________________________________________
David E. Chardavoyne, General Manager, (831) 755-4860
Attachments:
1. Draft Nacimiento Dam Operation Policy
2. Written comments received from subcommittee members
3. Board Order