Panorama of agricultural irrigation in the San Benito basin

Key Issues

  • Need to conjunctively manage imported water, local surface water, groundwater and recycled water
  • Maintenance of comprehensive and meaningful monitoring and data management programs for groundwater production, levels, and quality
  • Need to manage groundwater levels to minimize local high groundwater levels and provide supply during drought
  • Management of groundwater quality to ensure high quality supply for municipal supply and high-value crops
  • Regular reporting of the state of the basin to promote public awareness

Solutions

  • SGMA Planning
  • Groundwater monitoring program review
  • Numerical modeling
  • Annual Groundwater Reports
  • Local Groundwater Assistance grants
  • Water quality data management system and updates
  • Water balance updates
  • Salt and Nutrient Management Plan

Groundwater Basin Management

San Benito County Water District,
San Benito County, California

The San Benito County Water District manages its major groundwater basins in conjunction with imported water supplies, local surface water sources, and recycled water to maintain groundwater storage for sustainable supply and provide good quality water for agricultural and municipal users.

Todd Groundwater has worked with San Benito County Water District on numerous groundwater projects since 1988 including update of the Groundwater Management Plan (GWMP). Todd updated the basin water balance, provided numerical modeling, and evaluated salt loading. Todd has also prepared the Urban Water Management Plan for the Hollister Urban Area.

For the management plan, Todd Groundwater conducted an evaluation of the basin hydrogeology and changes in groundwater storage due to decades of managed recharge. Todd recognized that additional groundwater quality data were needed to make informed management decisions such as the location of recharge structures and groundwater extraction areas. To fill this gap, Todd and the District successfully applied for a Local Groundwater Assistance (AB303) Act grant to develop a water quality data management and monitoring program.

Subsequently, Todd Groundwater and the District joined forces to secure another AB303 grant for the installation and testing of a nested monitoring well in an area where the District seeks to manage groundwater quality and shallow groundwater levels for potential municipal groundwater production and groundwater banking. The project involved installation of a 770-foot deep dedicated monitoring well capable of monitoring five distinct vertical zones.

Todd Groundwater also prepares the Annual Groundwater Reports in accordance with the District's founding legislation and water code sections. The report provides a “state of the basin” summary that involves compilation, review, and analysis of data from the District's ongoing monitoring program. The Annual Reports also include evaluation of overdraft, documentation of groundwater production, evaluation of next-year agricultural pumping and water purchases, and recommendations for surface deliveries, replenishment, and groundwater charges. Recent Annual Reports include triennial updates of water balance and water quality conditions, and special studies that have addressed land use changes, demand and supply, and the 2014 Sustainable Groundwater Management Act (SGMA).

Planning for SGMA has included public outreach presenting the SGMA process and timelines, evaluation of groundwater basin boundary issues, and coordination with neighboring Groundwater Sustainability Agencies (GSAs). The District, with Todd assistance, filed its notification to become an exclusive GSA in February 2017. Subsequently, the District plans to prepare a Groundwater Sustainability Plan with completion and adoption prior to the 2022 deadline.