Title
Consider receiving the Deep Aquifers Management Recommendations Memorandum.
Report
RECOMMENDATION:
It is recommended that the Monterey County Water Resources Agency Board of Directors:
Receive the Deep Aquifers Management Recommendations Memorandum.
SUMMARY/DISCUSSION:
The Deep Aquifers Management Recommendations Memorandum (“Memo,” Attachment 1) was developed collaboratively by the Salinas Valley Basin Groundwater Sustainability Agency (“SVBGSA”), Monterey County Water Resources Agency (“MCWRA”), County of Monterey, and Marina Coast Water District Groundwater Sustainability Agency (“MCWDGSA”) to provide a framework for protecting and sustainably managing the Deep Aquifers as a groundwater resource. The Memo builds upon the 2024 Deep Aquifers Study (“Study”) and subsequent groundwater sustainability evaluations and data collection efforts.
In portions of the Salinas Valley, the Deep Aquifers are an increasingly important source of groundwater for agricultural, municipal, industrial, and domestic uses. Historically considered a strategic reserve, these deeper groundwater formations are now experiencing increased extraction as seawater intrusion and declining water quality affect shallower overlying aquifers.
The Study found that groundwater levels in the Deep Aquifers have declined over the past two decades, resulting in groundwater elevations below those of overlying aquifers in many locations. This has resulted in a reversal of historical hydraulic gradients that increases the risk of both lateral seawater intrusion from the coast and downward migration of degraded groundwater from the 180-Foot and 400-Foot Aquifers. The Study also documented ongoing groundwater storage losses, estimated at approximately 9,000 to 9,600 acre-feet annually, and identified areas of concentrated pumping near Castroville, west of Salinas, and within the Seaside region.
Recent Groundwater Sustainability Plan (“GSP”) evaluations completed since the Study was published further indicate that groundwater level sustainability thresholds have been exceeded consistently in the Deep Aquifers since the GSPs were prepared. Monitoring data show continued groundwater level declines and increasing vulnerability to seawater intrusion. SVBGSA and MCWDGSA have expanded the Deep Aquifers monitoring networks to address data gaps, installing new dedicated Deep Aquifers monitoring wells, and improving groundwater models to better understand aquifer conditions and guide management decisions.
To address these concerns, the Memo recommends a combination of interim and long-term management actions. Near-term actions include development of a Seawater Intrusion Response Plan, implementation of demand management measures where groundwater sustainability concerns are most acute, evaluation of well permitting policies, and continuation of well destruction programs to eliminate anthropogenic pathways that could facilitate movement of seawater intruded groundwater between aquifers. These measures are intended to provide immediate protection while longer-term water supply and recharge projects are developed.
The Memo also identifies a portfolio of long-term projects designed to reduce dependence on Deep Aquifers pumping and restore groundwater levels. These include expansion and optimization of recycled water delivery systems, aquifer storage and recovery projects, brackish groundwater treatment and reuse, decentralized recharge projects, indirect potable reuse, desalination, and operational changes that improve management of existing groundwater supplies. Collectively, these projects are intended to diversify regional water supplies, enhance groundwater replenishment, and support long-term compliance with Sustainable Groundwater Management Act (“SGMA”) requirements.
The Memo emphasizes that management of the Deep Aquifers must occur through existing statutory authorities, adopted Groundwater Sustainability Plans, and established governance structures. It does not create new regulatory requirements but instead provides a technical and policy framework for future consideration by local governing boards. Continued interagency coordination, adaptive management, and monitoring will be essential to protect the Deep Aquifers as a long-term water supply resource while maintaining local control of groundwater management under SGMA.
The Memo was part of the discussion on May 20, 2026, at an informational workshop hosted by MCWRA, SVBGSA, MCWDGSA, and the County of Monterey. An overview of the Monitoring Plan for the Deep Aquifers (“Monitoring Plan”), which is described in Section 4.3 of the Memo, was presented to the Board of Directors in November 2025. The Monitoring Plan was adopted by the MCWRA Board of Supervisors in December 2025, at the same time that a Memorandum of Understanding was executed by MCWRA to memorialize coordination among agencies toward implementation of the Monitoring Plan.
OTHER AGENCY INVOLVEMENT:
The Memo was developed collaboratively with the SVBGSA, MCWDGSA, and County of Monterey.
FINANCING:
There is no financial impact to receive this report. Funding for preparation of the Memo was provided in part by a grant awarded to MCWDGSA by the California Department of Water Resources. MCWRA’s groundwater monitoring activities in the Deep Aquifers are part of the Groundwater Monitoring Program, which is included in MCWRA’s FY 25/26 Adopted Budget and in the proposed FY 26/27 budget.
Prepared by: Amy Woodrow, Senior Hydrologist, (831) 755-4860
Approved by: Ara Azhderian, General Manager, (831) 755-4860
Attachments:
1. Deep Aquifers Management Recommendations Memorandum