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.

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.

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

• Revised Scope of Work to Redetermine the Sustainable Yield by 2025
• Methods to Estimate Annual Storage Change in the Borrego Springs Subbasin
• Consideration of Action on an Application for New De Minimis Pumping
• Recommended Technical Scope of Work and Budget for WY 2022 and 2023

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.

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. This scope of work was approved by the Watermaster Board 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 is listed below, along with memos documenting each completed task:

• Task 1 – Compare FMP-Estimated Pumping to Actual Pumping for WY 2022
• Task 2 – Update Water-Use Factors in the FMP
• Task 3 – Correct Errors Identified in the 2021 BVHM
• Task 4 – Perform Model Recalibration
• Task 5 – Determine the Sustainable Yield