Title
Consider adopting a release schedule for Nacimiento and San Antonio reservoirs for 2025. (Staff Presenting: Peter Kwiek)
Report
RECOMMENDATION:
It is recommended that the Monterey County Water Resources Agency Board of Directors:
Adopt a Release Schedule for Nacimiento and San Antonio Reservoirs for 2025.
SUMMARY/DISCUSSION:
In most years, continuous reservoir releases are made during the “conservation season” (April-October) to optimize Salinas Valley groundwater recharge as well as Salinas River Diversion Facility (SRDF) operations. These conservation releases are guided by a schedule developed each year in late winter to early spring by staff to approximate the expected sequence of reservoir withdrawals that fully accounts for a complex set of obligations, constraints and, to the extent possible, hydrologic conditions.
Key obligations include annual withdrawal limits and conditions-based prescribed flows supportive of federally listed species. Both are stipulated in the water rights that authorize the Agency to store, withdraw and re-divert waters of the state within the Nacimiento, San Antonio and Salinas River watersheds. Constraints are of physical, administrative and environmental nature. Physical constraints include elevation-dependent limits on methods and rates of releases as well as safe operating limits of release mechanisms; administrative constraints include guaranteed water allotments established by contractual agreements. Minimum required releases, required lagoon bypass flows, as well as limits on release rate changes are among the environmental constraints accounted for in the development of the annual release schedule.
The Agency has made releases during 12 of the 16 summer conservation seasons since the Salinas River Diversion Facility (SRDF) began operating in 2010. Two extended droughts resulted in insufficient reservoir levels to operate from 2014-2016 and in 2022. More recently, 2023 and 2024 marked a return to wet conditions providing large storage increases at both Reservoirs and enough water to fully operate in both years and also in 2025. Combined storage as of March 20, 2025 was sufficient to plan a third consecutive full diversion season this year, despite limited net inflow totals (approximately 64,000 acre-feet at Nacimiento, approximately 11,000 acre-feet at San Antonio this winter).
The attached proposed 2025 release schedule accounts for current reservoir inflow rates but assumes no new inflow events for the remainder of the calendar year. The schedule also reflects an estimation of reservoir releases needed to maintain flow to the Salinas River Lagoon in support of steelhead outmigration and habitat, as stipulated in water rights authorizing the Agency to operate the reservoirs and the SRDF. Temporary release adjustments are also incorporated into the proposed schedule in consideration of recreation activities over summer holiday periods.
As presented to the Reservoir Operations Advisory Committee at its March meeting, the attached release schedule was originally based on an SRDF startup the first week of April with continuous conservation flows to recharge the Salinas Valley groundwater basin and operate the SRDF into mid-October while meeting the operational requirements of State Water Resources Control Board appropriative water rights held by the Agency for the Nacimiento and San Antonio Rivers The SRDF startup date was subsequently shifted to mid-April based on an updated assessment of watershed conditions, water rights requirements and water use demands.
As is the standard procedure each year, the release schedule will be updated monthly based on actual weather and river conditions, changing SRDF demands, and other reservoir operational considerations as may be necessary subsequent to the adoption of this release schedule.
OTHER AGENCY INVOLVEMENT:
At its March 27, 2025 meeting, the Reservoir Operations Advisory Committee recommended that The Board of Directors consider adopting the attached reservoir release schedule.
FINANCING:
None
Prepared by: Peter Kwiek, Associate Water Resources Hydrologist (831) 755-4860
Attachments:
1. Reservoir Release Schedule For 2025
2. Board Order