Technical Advisory Committee

The TAC is an advisory body established pursuant to Section IV.G(1) of the Judgment to study technical aspects of the Basin and to issue recommendations to Watermaster based on such technical study for the purpose of achieving Sustainable Groundwater Management in the Basin in an effective and efficient manner, consistent with the rights and obligations of the Parties established by this Judgment.

The Watermaster Board has established and adopted guidelines for TAC membership and the roles/responsibilities of the TAC and the Technical Consultant. Membership of the TAC is open to an expert hired by any Party holding BPA or the County of San Diego.

TAC Member Bios

Bob Wagner, PE (Principal Water Resources Engineer, Wagner & Bonsignore) – representing AAWARE. Mr. Wagner has over 30 years of experience in water resources engineering. He currently serves as the Watermaster Engineer for the Mojave Basin Area Watermaster.

Tom Watson, PG (Principal Geologist, Aquilogic) – representing Rams Hill. Mr. Watson has over 35 years of experience in environmental and groundwater management. He was previously involved in overseeing all of the water resources management programs for the City of Santa Monica and is currently involved in the development of Groundwater Sustainability Plans (GSPs) for numerous clients in California.

Trey Driscoll, PG, CHG (Principal Hydrogeologist, Intera) – representing Borrego Water District. Mr. Driscoll has 20 years of experience in hydrogeology and groundwater management. He was the project manager from Dudek (consultant to the County of San Diego) for the development of the GSP for the Borrego Springs Groundwater Subbasin and has been involved in technical work in the Borrego Springs subbasin for over five years.

Jim Bennett, PG, CHG (County of San Diego) – representing the County of San Diego. Mr. Bennett has 23 years of experience in hydrogeology. Mr. Bennett was the manager of the development of the GSP for the Borrego Springs Groundwater Subbasin. He sits on the Borrego Springs Watermaster Board, representing the County of San Diego.

John Peterson, PG, CHG (retired) – representing the Roadrunner Club. Mr. Peterson has 40 years experience in hydrogeology and groundwater management including in the Borrego Valley. He previously was the San Diego County Groundwater Geologist where he established the Borrego Valley Groundwater Network. He also sits on the Borrego Springs Sponsor Group (Vice Chair), chairs the Water and Land Use Subcommittee of the Sponsor Group, and is a member of the Environmental Working Group of the Borrego Springs Watermaster.

Dr. Russell Detwiler (University of California, Irvine) – representing the Borrego Springs Community. Professor Detwiler has over 30 years of experience in hydrogeology as a practitioner, a research scientist and, most recently, as an Associate Professor in the Civil and Environmental Engineering department at UCI. His research combines experimental (laboratory- and field-scale) and modeling studies of groundwater flow and transport processes in pore-scale to basin-scale systems.

TAC Facilitation

The Technical Advisory Committee is facilitated by the Watermaster’s Technical Consultant, Andy Malone, PG. The Technical Consultant is a non-voting member of the TAC.

Andy Malone, PG (Principal Geologist, West Yost) – Mr. Malone has 25 years of experience in geology and groundwater management. He also leads technical committees and provides technical services for the Chino Basin Watermaster and the Six Basin Watermaster in southern California.

TAC Recommendations to the Watermaster Board

Redetermine the Sustainable Yield by 2025

The Borrego Valley Hydrologic Model (BVHM) and its supporting tools, the Basin Characterization Model (BCM) and MODFLOW-OWHM with the Farm Process (FMP), were used to characterize the water budget and Sustainable Yield for the Borrego Springs Subbasin. Section II.E of the Judgment established the initial Sustainable Yield at 5,700 acre-feet per year (afy) and requires it to be redetermined by January 1, 2025, and every five years thereafter through 2035.

As described in the memos below, the Watermaster has completed the first redetermination of the Sustainable Yield for 2025. The 2025 Sustainable Yield is 7,952 afy. Based on the redetermined Sustainable Yield, the Rampdown schedule was revised to reach 7,952 afy by WY 2040.

The TAC identified understanding the ability of the BVHM to accurately estimate historical and future pumping as the top priority issue to address in the 2025 redetermination of the Sustainable Yield. The TAC recommended to the Watermaster Board a technical scope-of-work and budget for water years (WYs) 2023 and 2024 to update the BVHM and Redetermine the Sustainable Yield by 2025. The Watermaster Board approved a scope of work at its meeting on February 9, 2023. The work planned for WYs 2022, 2023 and 2024 was included in a Sustainable Groundwater Management (SGM) grant application that has been awarded by the DWR.

The scope of work was executed by the Watermaster’s Technical Consultant in collaboration with the TAC and the Watermaster Board. The results and conclusions of the work have been documented in the 2025 Sustainable Yield Technical Report. Each memo documenting each completed task is also listed below:

TAC Meetings

WY 2026 Meeting Agendas, Packets, and Approved Minutes

Note: Ad-Hoc TAC meetings do not have meeting minutes

WY 2025 Meeting Agendas, Packets, and Approved Minutes

Note: Ad-Hoc TAC meetings do not have meeting minutes

WY 2024 Meeting Agendas, Packets, and Approved Minutes

Note: Ad-Hoc TAC meetings do not have meeting minutes

WY 2023 Meeting Agendas, Packets, and Approved Minutes

WY 2022 Meeting Agendas, Packets, and Approved Minutes

WY 2021 Meeting Agendas, Packets, and Approved Minutes

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