Improving Groundwater Security in the United States

The White House | December 14th, 2024

The U.S. is facing a serious and unprecedented groundwater challenge. In many aquifers, groundwater withdrawal has outpaced natural recharge, which is exacerbated by the

The U.S. is facing a serious and unprecedented groundwater challenge. In many aquifers, groundwater withdrawal has outpaced natural recharge, which is exacerbated by the changing climate and precipitation variability. Much of the water in the major aquifers in the U.S. is fossil water, recharged over 10,000 years ago, and will not be replaced naturally on human timescales. In the western U.S., groundwater resources are being depleted at alarming rates, mostly from agricultural withdrawal. The depletion has caused land subsidence and earth fissures as well as permanent reduction of storage capacity. The depletion has national and global consequences as non-renewable groundwater in the west is embedded in agricultural products transported to the rest of the U. S. and in agricultural commodities exported globally. Many federal agencies have programs to measure the quality and quantity of groundwater, as well as conservation programs for sustainable use of groundwater. PCAST applauds and endorses their efforts as well as those by state governments, non-governmental organizations, professional organizations, local communities, private citizens, and others, to manage their groundwater resources. To ensure the sustainability of this indispensable resource and mitigate risks from its depletion, it is imperative that we enhance our understanding and management of groundwater resources.

Incomplete Determination of the 2020 Eastern San Joaquin Subbasin Groundwater Sustainability Plan

California Department of Water Resources (DWR) | January 28th, 2022

The Department of Water Resources (Department) has evaluated the groundwater sustainability plan (GSP) submitted for the Eastern San Joaquin Subbasin (Subbasin) and has d

The Department of Water Resources (Department) has evaluated the groundwater sustainability plan (GSP) submitted for the Eastern San Joaquin Subbasin (Subbasin) and has determined that the GSP is incomplete. The Department based its determination on recommendations from the Staff Report, included as an enclosure to the attached Statement of Findings, which describes that the Eastern San Joaquin Subbasin GSP does not satisfy the objectives of the Sustainable Groundwater Management Act (SGMA) nor substantially comply with the GSP Regulations. The Staff Report also provides corrective actions which the Department recommends to address the identified deficiencies.

Incomplete Determination of the 2020 Groundwater Sustainability Plans Submitted for the San Joaquin Valley – Kern County Subbasin

California Department of Water Resources (DWR) | January 28th, 2022

Department management has reviewed the enclosed Staff Report, which recommends that the deficiencies identified should preclude approval of the Plan. Based on its review

Department management has reviewed the enclosed Staff Report, which recommends that the deficiencies identified should preclude approval of the Plan. Based on its review of the Staff Report, Department management is satisfied that staff have conducted a thorough evaluation and assessment of the Plan and concurs with, and hereby adopts, staff’s recommendation and all the corrective actions provided. The Department thus deems the Plan incomplete based on the Staff Report and the findings contained herein. A. The GSPs do not establish undesirable results that are consistent for the entire Subbasin. 1. While the Coordination Agreement presents Subbasin-wide undesirable results, the Subbasin’s fragmented approach towards establishing management criteria that define undesirable conditions in various parts of the Subbasin does not satisfy SGMA’s requirement to use same data and methodologies. B. The Subbasin’s chronic lowering of groundwater levels sustainable management criteria do not satisfy the requirements of SGMA and the GSP Regulations. 1. The GSPs relied on disparate methods to develop groundwater level minimum thresholds across the numerous GSPs and management areas. 2. The GSPs do not consistently and sufficiently document the effects of their selected minimum thresholds on beneficial uses and users in the Subbasin, nor explain how the minimum thresholds and measurable objectives that are set below historical lows will impact other applicable sustainability indicators, specifically water quality, land subsidence, and reduction of groundwater storage. C. The Subbasin’s land subsidence sustainable management criteria do not satisfy the requirements of SGMA and the GSP Regulations. 1. The Plan lacks a Subbasin-wide, coordinated approach to establishing land subsidence sustainable management criteria. 2. The GSPs and management areas that use their minimum thresholds for the chronic lowering of groundwater levels as proxy criteria for subsidence do not sufficiently demonstrate that groundwater levels (specifically groundwater levels below historical lows) are a reasonable proxy to avoid land subsidence that would substantially interfere with surface land uses.

Indian Wells Valley Groundwater Basin Groundwater Sustainability Plan

Indian Wells Valley Groundwater Authority (IWVGA) | January 14th, 2020

Currently, the groundwater resources in the Indian Wells Valley Groundwater Basin (IWVGB or Basin) are not being sustainably managed. Overdraft conditions have existed fo

Currently, the groundwater resources in the Indian Wells Valley Groundwater Basin (IWVGB or Basin) are not being sustainably managed. Overdraft conditions have existed for decades as a result of groundwater pumping that exceeds the natural Basin yield (Dutcher and Moyle, 1973). The results of overdraft have manifested themselves through various undesirable results, primarily the chronic lowering of groundwater levels, the degradation of water quality, and the reduction of groundwater in storage throughout the IWVGB. (See Section 3 for a discussion of overdraft conditions in the Basin.) In compliance with the Sustainable Groundwater Management Act (SGMA), as set forth in California Water Code (CWC) Section 10720.1, this Groundwater Sustainability Plan (GSP) discusses Basin management strategies that will culminate in the absence of undesirable and unsustainable groundwater conditions in the IWVGB. The GSP recommends management actions and projects, and provides measurable sustainability objectives and milestones that are intended to achieve Basin sustainability while considering the unique geologic and hydrogeologic conditions of the IWVGB. The recommendations of this GSP will provide for long-term sustainable groundwater management in the IWVGB within 20 years of GSP implementation. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7

Integrated simulation of consumptive use and land subsidence in the Central Valley, California, for the past and for a future subject to urbanization and climate change

U.S. Geological Survey (USGS) | October 17th, 2010

Competition for water resources is growing throughout California, particularly in the Central Valley where about 20% of all groundwater used in the United States of Ameri

Competition for water resources is growing throughout California, particularly in the Central Valley where about 20% of all groundwater used in the United States of America is consumed for agriculture and urban water supply. Continued agricultural use coupled with urban growth and potential climate change would result in continued depletion of groundwater storage and associated land subsidence throughout the Central Valley. For 1962–2003, an estimated 1230 hectametres (hm3) of water was withdrawn from fine-grained beds, resulting in more than three metres (m) of additional land subsidence locally. Linked physically-based, supply-constrained and demand-driven hydrological models were used to simulate future hydrologic conditions under the A2 climate projection scenario that assumes continued “business as usual” greenhouse gas emissions. Results indicate an increased subsidence in the second half of the twenty-first century. Potential simulated land subsidence extends into urban areas and the eastern side of the valley where future surface-water deliveries may be depleted.

It is the Discharge

National Groundwater Association (NGWA) | September 1st, 2007

We all know the mantra Keep It Simple—the principle KISS. I have been thinking of another mantra for ground water—It Is the Discharge. Let me explain: In a re

We all know the mantra Keep It Simple—the principle KISS. I have been thinking of another mantra for ground water—It Is the Discharge. Let me explain: In a recent conversation with one of my distinguished colleagues, he bemoaned our lack of understanding of ground water recharge. I keep thinking about that conversation. In a broad sense as hydrogeologists, we are hoping to understand how aquifer systems function, more particularly how much water is flowing through a particular system—the focus on recharge is simply one facet of the larger task. In studying the system, there are at least three aspects that we can focus on—(1) the recharge; (2) the aquifer itself as a transmission mechanism; and (3) the discharge from the aquifer.

James Groundwater Sustainability Agency Groundwater Sustainability Plan

James Groundwater Sustainability Agency (JGSA) | December 12th, 2019

Kaweah Subbasin Probationary Hearing Draft Staff Report

California State Water Resources Control Board (SWRCB) | May 2nd, 2024

The State Water Board recognizes that local public agencies in the Kaweah Subbasin have made significant efforts since the passage of SGMA to form three groundwater susta

The State Water Board recognizes that local public agencies in the Kaweah Subbasin have made significant efforts since the passage of SGMA to form three groundwater sustainability agencies (GSAs) and then develop detailed technical and other information supporting the adoption and implementation of three groundwater sustainability plans (GSPs) for the subbasin. Despite those efforts, in January of 2020, DWR reviewed the three GSPs to determine if the GSPs met SGMA’s requirements and found the GSPs to be incomplete. Following revisions made by the GSAs in the subbasin, DWR reevaluated the GSPs in March of 2023, determined the GSPs to be inadequate, and referred the subbasin to the State Water Board, as required by SGMA. Consistent with SGMA, the State Water Board may now consider whether to designate the Kaweah Subbasin as a “probationary basin,” a term that is used in SGMA to describe a basin in the first stage of state intervention.  Click here for Water Board updates on hearings. A January 5, 2025 has been cancelled to allow more time to review updated groundwater sustainability plans.

Kaweah Subbasin Staff Assessment

California State Water Resources Control Board (SWRCB) | October 14th, 2025

The Kaweah Subbasin is managed by three GSAs: East Kaweah GSA, Greater Kaweah GSA, and Mid-Kaweah GSA (collectively, the Kaweah GSAs or GSAs). Each GSA wrote their own GS

The Kaweah Subbasin is managed by three GSAs: East Kaweah GSA, Greater Kaweah GSA, and Mid-Kaweah GSA (collectively, the Kaweah GSAs or GSAs). Each GSA wrote their own GSP, East Kaweah GSP (EKGSP), Greater Kaweah GSP (GKGSP), and Mid-Kaweah GSP (MKGSP). The three GSPs are tied together by a coordination agreement. The primary use of groundwater within the subbasin is irrigated agriculture; in 2020, irrigated agriculture used more than 94 percent of the groundwater in the subbasin (2024 Coordination Agreement, Appendix 1, p. 27). The subbasin is critically overdrafted, which means that groundwater is pumped out of the subbasin faster than it is recharged by precipitation and other sources. On average, the amount pumped from the subbasin in a year is 104,000 acre-feet greater than the amount recharged (2024 GKGSP p. 1-1). Overdraft can cause the land surface to sink, potentially damaging infrastructure and reducing aquifer storage. In addition, overdraft threatens groundwater levels and drinking water quality and could have disparate impacts on communities that rely on shallower groundwater levels. Due to historic and political factors, many of these are economically disadvantaged and communities of color. As of 2022, the subbasin has an estimated population of 296,632 people with most of the population being Hispanic or Latino (60.6%) followed by white (31%) (American Community Survey, 2022). The average annual household income within the subbasin in 2022 is $71,000, which is significantly less than the state average of $91,551 (ibid.).

Kern County Subbasin Groundwater Sustainability Plan 2025

Kern County Subbasin Groundwater Sustainability Agency (KCSGSA) | August 29th, 2025

The Kern Subbasin (Kern Subbasin) Amended Groundwater Sustainability Plan (2025 Plan)  presents the overview of each of the seven GSPs that together constitute the 2025

The Kern Subbasin (Kern Subbasin) Amended Groundwater Sustainability Plan (2025 Plan)  presents the overview of each of the seven GSPs that together constitute the 2025 Plan, including which GSAs are covered by each GSP and whether the GSP includes supplemental “blue pages” specific to the portion of the Kern Subbasin that the GSA manages consists of seven closely coordinated (and nearly identical) Groundwater Sustainability Plans (GSPs) and the Kern Subbasin Coordination Agreement. The 2025 Plan represents a critical milestone in the Kern Subbasin and all 20 Kern Subbasin Groundwater Sustainability Agencies’ (GSAs) ongoing commitment to achieving long-term groundwater sustainability under California’s Sustainable Groundwater Management Act (SGMA). Developed collaboratively by all 20 GSAs, the 2025 Plan responds directly to regulatory feedback from the California Department of Water Resources (DWR) and the State Water Resources Control Board (SWRCB), incorporating the latest data, technical refinements, and input from interested parties.