Approaches for groundwater management in times of depletion and regulatory change

University of California, Davis (UC Davis) | June 1st, 2018

New legislation and related regulations in California mandate groundwater management to avoid undesirable results from excessive groundwater pumping and other hum

New legislation and related regulations in California mandate groundwater management to avoid undesirable results from excessive groundwater pumping and other human activities. Required aspects of management planning that will occur in well over 100 alluvial groundwater sub-basins across the state include scientific foundation and public transparency. While the details of individual groundwater management approaches will be particular to conditions in each management area, there will be common elements based on similar aspects of many groundwater systems in the state. The process of beginning to implement groundwater management for a large part of the state poses challenges. Use of scientific knowledge and methods of analysis developed in academia and industry will be helpful to the overall effort. This dissertation considers aspects of groundwater management that are expected to be common among many planning efforts. Inactive water supply wells acting as conduits for contaminant migration is considered through field examples and use of recently available databases regarding existing well constructions and water quality. Nonpoint source pollution effects on groundwater quality from conduit wells are investigated and selective regulatory action is explored as an option for addressing an issue that is too large for complete solution with available resources. Options for managed aquifer recharge are explored for a combined urban-agricultural area through use of a recently released land use database. A hydro-economic analysis is performed using linear programming to evaluate the efficacy of an on-farm recharge approach. Future work may include development of additional insights within the context of the study areas presented as well as extensions that consider new geographic areas and additional related considerations.

Approved Determination of the Revised Groundwater Sustainability Plan Submitted for the San Joaquin Valley – Merced Subbasin

California Department of Water Resources (DWR) | August 4th, 2023

Assessing Natural Recharge in Indian Wells Valley, California: A Basin Characterization Model Case Study

U.S. Geological Survey (USGS) | March 18th, 2026

The communities in Indian Wells Valley (IWV), in the northern Mojave Desert in California, rely on groundwater for domestic and agricultural use. Mountain front recharge

The communities in Indian Wells Valley (IWV), in the northern Mojave Desert in California, rely on groundwater for domestic and agricultural use. Mountain front recharge from the surrounding Sierra Nevada is the main source of natural recharge to the valley. Increased urbanization, agricultural development, and groundwater pumping during recent decades put IWV in a state of critical overdraft. The U.S. Geological Survey Basin Characterization Model, version 8 (BCMv8) was used to evaluate historical and future climate and hydrologic conditions in IWV. The BCMv8 estimated natural recharge in IWV at 10.7 million cubic meters (Mm3) per year for the period from 1981 to 2010. Future patterns of water balance variables using three future climate scenarios, hot- wet, hot-dry, and warm-moderately wet, were calculated for mid-century (2040–69) and end-of-century (2070–99) periods. Results for both wet models projected an increase in recharge in both periods, whereas the hot-dry model projected a decrease in recharge in both periods. All models reported a large increase in seasonal variability in recharge, indicating more future availability and frequent occurrences of drought years. All climate scenarios projected an increase in climatic water deficit in both periods. These increases in irrigation demand and variability of water supply highlight the importance of strategic management planning for the sustainability of water resources in IWV.

Assessment of Interconnected Subbasins

Butte County | June 30th, 2017

The Sustainable Groundwater Management Act (SGMA) requires groundwater sustainability agencies (GSAs) to develop groundwater sustainability plans (GSPs) that achieve sust

The Sustainable Groundwater Management Act (SGMA) requires groundwater sustainability agencies (GSAs) to develop groundwater sustainability plans (GSPs) that achieve sustainable groundwater management within 20 years of adoption. All critically overdrafted basins must adopt GSPs by January 31, 2020; all other medium and high priority basins must complete GSPs by January 31, 2022. Since many subbasins are hydrologically connected to adjoining subbasins, sustainable groundwater management will require accounting for groundwater interactions with adjoining subbasins. Often, adjoining subbasins will use different analytical methods or apply different levels of technical rigor. Many GSAs are concerned that different methodologies for developing interbasin flows can lead to different results that will call into question the ability to achieve sustainability and would potentially create issues with SGMA compliance. This effort evaluated opportunities and barriers for agencies to account for interconnected basin dynamics through the collaboration of technical experts focused on a portion of the northern Sacramento Valley Integrated Regional Water Management (NSVIRWM) Plan area. As interbasin flows (i.e., groundwater flow between interconnected basins) cannot be directly measured, the project reviewed available tools to investigate how they may or may not be suitable for use in estimating interbasin flows within the region. This process highlighted areas for local agencies to consider in addressing interbasin issues, developed a framework for analysis in other areas of the state, and identified areas where the state and federal government can assist local agencies implementing SGMA. This report is developed to provide summary level information appropriate for decision makers, with more detailed technical information and examples provided in the appendices or by reference. Interbasin flow is groundwater entering or exiting a defined subbasin through its boundaries in the subsurface and may vary significantly in space and time based on the dynamics of inflow and outflow from the basins. Interbasin flows are driven by differences in groundwater levels (i.e. head gradients) across the basin boundary. Groundwater levels are, in turn, impacted by processes on the land surface. Land use and crop acreages drive water demand in a subbasin and indirectly drive groundwater pumping, which has a direct effect on groundwater levels (i.e., groundwater heads). The direction and magnitude of interbasin flow depends on the groundwater head gradient across the basin boundary and the conductivity of the aquifer materials. It is widely recognized that the groundwater subbasins in the Sacramento Valley, and throughout the Central Valley, are interconnected to varying degrees. The Sacramento Valley Groundwater Basin includes many subbasins, extends over a wide geographic area, and includes numerous established and eligible GSAs. With interconnected subbasins, management decisions and actions in one subbasin may influence one or more adjoining subbasins. Such influence may positively or negatively impact sustainability. Thus, interbasin flows become critical to both GSAs’ development of GSPs and to DWR reviewing GSPs.

Assessment of Interconnected Subbasins: Regional Collaboration and Model Selection Process

Groundwater Resources Association of California (GRA) | October 3rd, 2017

In basins with complex spatial and temporal variations in water budget components, integrated groundwater-surface water modeling is the best approach to quantify and eval

In basins with complex spatial and temporal variations in water budget components, integrated groundwater-surface water modeling is the best approach to quantify and evaluate interbasin groundwater flows.

At Risk: Public Supply Well Vulnerability Under California’s Sustainable Groundwater Management Act

Pacific Institute | June 1st, 2021

Basin Boundary Adjustment Regulation Fact Sheet

California Department of Water Resources (DWR) | October 16th, 2015

In September 2014, the Governor signed into law the Sustainable Groundwater Management Act (SGMA). The Department has developed a program and is currently implementing ne

In September 2014, the Governor signed into law the Sustainable Groundwater Management Act (SGMA). The Department has developed a program and is currently implementing new and expanded responsibilities identified in SGMA. One of these responsibilities is developing emergency regulations to modify groundwater basin boundaries. SGMA established a process for local agencies to request that DWR revise the boundaries of a groundwater basin or subbasin, including the creation of new subbasins.

Basin Framework for a Multi-benefit Groundwater Replenishment and Water Trading Program: Groundwater Sustainability Plan Chapter Template

Environmental Defense Fund (EDF) | October 1st, 2018

The following Groundwater Sustainability Plan (GSP) chapter templates were developed by Environmental Defense Fund and New Current Water and Land, LLC to assist Groundwat

The following Groundwater Sustainability Plan (GSP) chapter templates were developed by Environmental Defense Fund and New Current Water and Land, LLC to assist Groundwater Sustainability Agencies (GSAs) with incorporating multi-benefit replenishment and water trading mechanisms into GSPs. These chapter templates provide an initial framework that can be adapted to reflect regional conditions and objectives. Achieving groundwater sustainability in many overdrafted basins is contingent upon collaboration between landowners/pumpers/operators (“operators”) and GSAs to replenish groundwater. Chapter [X] Multi-Benefit Groundwater Replenishment outlines mechanisms to encourage and incentivize operator engagement in groundwater replenishment projects, with opportunities to pair these efforts with community and natural resource values, such as habitat creation and improved drinking water quality. When properly designed, groundwater trading programs can assist in efficient allocation of scarce resources, while avoiding negative third party impacts. Chapter [Y]: Water Trading provides a framework for implementation of groundwater trading programs as a groundwater management mechanism. Appendix A. outlines qualifying conditions that allow for streamlined approval of water trades.

BasinScout: Water Quantity

Freshwater Trust | January 16th, 2018

California’s Sustainable Groundwater Management Act (SGMA) establishes milestones that high- and medium-priority basins in a critical state of overdraft must meet to be

California’s Sustainable Groundwater Management Act (SGMA) establishes milestones that high- and medium-priority basins in a critical state of overdraft must meet to become sustainable. BasinScout can assist managers in building an objective allocation plan that reflects the needs of various stakeholders in shaping how sustainability is achieved.

Bear Valley Basin Groundwater Sustainability Plan

Bear Valley Basin Groundwater Sustainability Agency | June 15th, 2022

The GSP provides the geographical and managerial context of the Bear Valley Basin, summarizes the groundwater basin setting (including groundwater conditions, water budge

The GSP provides the geographical and managerial context of the Bear Valley Basin, summarizes the groundwater basin setting (including groundwater conditions, water budget, and management areas), describes the criteria used to measure and demonstrate sustainability, reviews the existing groundwater monitoring and management programs, and defines how those actions will be incorporated into the Bear Valley Basin GSP to achieve and maintain sustainability in the future.