California's Groundwater Conditions: Semi Annual Update May 2024, Spring Bulletin 118

California Department of Water Resources (DWR) | May 6th, 2024

In WY 2023, increased surface water supply led to a significant reduction in statewide groundwater extraction, amounting to a total annual extraction of 9.5 million acre-

In WY 2023, increased surface water supply led to a significant reduction in statewide groundwater extraction, amounting to a total annual extraction of 9.5 million acre-feet, a stark contrast to the 17 million acre-feet extracted in WY 2022.

California’s Water Market, By the Numbers, Update 2012

Public Policy Institute of California (PPIC) | November 21st, 2012

This report provides a check-up on California’s progress with two innovative water management tools: water marketing and groundwater banking. These tools are part o

This report provides a check-up on California’s progress with two innovative water management tools: water marketing and groundwater banking. These tools are part of a modern approach that will enable California to manage its scarce water resources more flexibly and sustainably.

Central Valley Flood Protection Plan 2022 (draft)

California Department of Water Resources (DWR) | April 21st, 2022

The Central Valley Flood Protection Plan (CVFPP) describes a programmatic vision for improving flood risk management throughout the Central Valley. Prepared by the Calif

The Central Valley Flood Protection Plan (CVFPP) describes a programmatic vision for improving flood risk management throughout the Central Valley. Prepared by the California Department of Water Resources (DWR) in accordance with the Central Valley Flood Protection Act of 2008 (Act) and adopted by the Central Valley Flood Protection Board (CVFPB) in June 2012, the CVFPP guides the State’s participation in managing flood risk in areas protected by the State Plan of Flood Control (SPFC). The Public Draft 2022 CVFPP Update is the second update required every five years by the Act. The CVFPP recommends actions and policies informed by engagement with stakeholders and partners and prioritizes investments over a 30-year horizon. Click here for the comment form, supporting documents, and DWR links.

Changing the course? What's worked, what hasn't and what's next for the SCWP: An assessment of the first three rounds of the Safe Clean Water Program

Los Angeles Waterkeeper (LA Waterkeeper) | February 16th, 2023

In 2018, Los Angeles County voters overwhelmingly approved “Measure W” — a 2.5 cent per square foot parcel tax on impervious surface on all land parcels within the

In 2018, Los Angeles County voters overwhelmingly approved “Measure W” — a 2.5 cent per square foot parcel tax on impervious surface on all land parcels within the LA County Flood Control District to fund multi-benefit stormwater infrastructure. The Safe Clean Water Program (SCWP) was developed to distribute and manage the funds raised, approximately $280M annually. The SCWP operates through three distinct programs: the District Program (10% of funds), the Municipal Program (40% of funds), and the Regional Program (50% of funds). The Regional Program has recently completed its third round of funding awarded through a competitive grant process. This assessment focuses on how the Regional Program is performing in achieving the SCWP’s overarching goals of water quality, water supply, and community investment benefits as provided in the ordinance authorizing this measure for the ballot. It also explores how well the program is meeting its goals around community engagement and support, benefits to disadvantaged communities, and green workforce development. The purpose of this assessment is to help the SCWP’s Regional Oversight Committee (ROC) and ultimately other decision-makers such as the LA County Board of Supervisors better understand what is working well with the program and where improvements could be made as part of the biennial review.

Climate-informed hydrologic modeling and policy typology to guide managed aquifer recharge

American Association for the Advancement of Science (AAAS) | April 21st, 2021

Harvesting floodwaters to recharge depleted groundwater aquifers can simultaneously reduce flood and drought risks and enhance groundwater sustainability. However, deploy

Harvesting floodwaters to recharge depleted groundwater aquifers can simultaneously reduce flood and drought risks and enhance groundwater sustainability. However, deployment of this multibeneficial adaptation option is fundamentally constrained by how much water is available for recharge (WAFR) at present and under future climate change. Here, we develop a climate-informed and policy-relevant framework to quantify WAFR, its uncertainty, and associated policy actions. Despite robust and widespread increases in future projected WAFR in our case study of California (for 56/80% of subbasins in 2070–2099 under RCP4.5/RCP8.5), strong nonlinear interactions between diversion infrastructure and policy uncertainties constrain how much WAFR can be captured. To tap future elevated recharge potential through infrastructure expansion under deep uncertainties, we outline a novel robustness-based policy typology to identify priority areas of investment needs. Our WAFR analysis can inform effective investment decisions to adapt to future climate-fueled drought and flood risk over depleted aquifers, in California and beyond.

Colusa County | Managed Aquifer Recharge: benefitting aquifers, farmers, and migratory birds

Nature Conservancy | September 3rd, 2018

In partnership with growers and the Colusa Groundwater Authority (CGA), The Nature Conservancy (TNC) is implementing a pilot multiple-benefit managed aquifer r

In partnership with growers and the Colusa Groundwater Authority (CGA), The Nature Conservancy (TNC) is implementing a pilot multiple-benefit managed aquifer recharge (MAR) program on farmland in California’s Central Valley, Colusa County. This program will benefit local groundwater users by replenishing critical domestic and agricultural groundwater supplies in a Severely Disadvanateged Community (SDAC). Participating farmers will benefit economically through incentive payments, and migratory shorebirds will benefit through the creation of critical winter habitat on farms through our specific field and water depth specificiations. MAR sites will be selected where and when it is appropriate and cost-effective to do so based on farming practices, soil suitability, water availability, basin water balances, and migratory/shorebird habitat requirements. The relevance and success of this program for Groundwater Sustainability Agencies (GSAs), Severely Disadvantaged Communities (SDACs), and Groundwater Sustainability Plans (GSPs) will require all of these stakeholders and project participants to collaborate on its design. Thus, TNC will engage growers, water managers, and other stakeholders in a variety of formal and informal ways to ensure that this program will meet the needs of all parties involved in GSP development. This program serves as a model for other GSAs and stakeholders seeking to deliver multiple benefits through on-farm recharge in the Central Valley where such a program is appropriate.

Comment on “Short-lived pause in Central California subsidence after heavy winter precipitation of 2017” by K. D. Murray and R. B. Lohman

American Association for the Advancement of Science (AAAS) | June 12th, 2019

In a study by Murray and Lohman (M&L), the authors suggest that remote sensing data are useful for monitoring land subsidence due to aquifer system compacti

In a study by Murray and Lohman (M&L), the authors suggest that remote sensing data are useful for monitoring land subsidence due to aquifer system compaction. We agree. To infer aquifer dynamics, we provide a more detailed and joint analysis of deformation and groundwater data. Investigating well data in the Tulare Basin, we find that groundwater levels stabilized before 2015 and show that M&L’s observed continued subsidence through July 2016 is likely caused by the delayed compaction of the aquitard. Our analysis suggests the observed 2017 transient uplift is not due to recharge of the aquifer system after heavy winter rainfall because it requires an unrealistic vertical hydraulic gradient nearly five orders of magnitude larger than that typical of Tulare Basin. We find that, regardless of the amount of rainfall, transient annual uplifts of ~3 cm occur in May to June. Using an elastic skeletal storage coefficient of 5 × 10−3, we link this ground uplift to annual groundwater level changes.

Conjunctive Water Management Resource Management Strategy

California Department of Water Resources (DWR) | April 29th, 2024

Conjunctive water management, also referred to as conjunctive use, is broadly defined as the coordinated and planned use and management of the different sources of water

Conjunctive water management, also referred to as conjunctive use, is broadly defined as the coordinated and planned use and management of the different sources of water in time and space. It is usually focused on surface water and groundwater resources to maximize the availability and reliability of water supplies in a region to meet various management objectives. It is a holistic approach to water resource management that can increase available water for beneficial uses, allow water agencies greater flexibility in scheduling deliveries, and improve drought resiliency (California Department of Water Resources 2003).

County of San Bernardino Hydrology Manual

San Bernardino County | August 1st, 1986

Coupling a spatiotemporally distributed soil water budget with stream-depletion functions to inform stakeholder-driven management of groundwater-dependent ecosystems

Water Resources Research, American Geophysical Union | November 12th, 2013

Groundwater pumping, even if only seasonal, may significantly impact groundwater-dependent ecosystems through increased streamflow depletion, particularly in semiarid and

Groundwater pumping, even if only seasonal, may significantly impact groundwater-dependent ecosystems through increased streamflow depletion, particularly in semiarid and arid regions. The effects are exacerbated, under some conditions, by climate change. In social sciences, the management of groundwater-dependent ecosystems is generally considered a “wicked” problem due to the complexity of affected stakeholder groups, disconnected legal frameworks, and a divergence of policies and science at the cross road between groundwater and surface water, and between ecosystems and water quality. A range of often simplified scientific tools plays an important role in addressing such problems. Here we develop a spatiotemporally distributed soil water budget model that we couple with an analytical model for stream depletion from groundwater pumping to rapidly assess seasonal impacts of groundwater pumping on streamflow during critical low flow periods. We demonstrate the applicability of the tool for the Scott Valley in Northern California, where protected salmon depend on summer streamflow fed by cool groundwater. In this example, simulations suggest that increased recharge in the period immediately preceding the critical low streamflow season, and transfer of groundwater pumping away from the stream are potentially promising tools to address ecosystem concerns, albeit raising difficult infrastructure and water trading issues. In contrast, additional winter recharge at the expense of later spring recharge, whether intentional or driven by climate may reduce summer streamflows. Comparison to existing detailed numerical groundwater model results suggests that the coupled soil water mass balance—stream depletion function approach provides a viable tool for scenario development among stakeholders, to constructively inform the search for potential solutions, and to direct more detailed, complex site-specific feasibility studies. The tool also identifies important field monitoring efforts needed to improve the understanding and quantification of site-specific groundwater-stream interactions.