Agricultural managed aquifer recharge (Ag-MAR)—a method for sustainable groundwater management: A review

Critical Reviews in Environmental Science and Technology (Taylor & Francis) | March 28th, 2022

More than two billion people and 40% of global agricultural production depend upon unsustainable groundwater extraction. Managed aquifer recharge (MAR), the practice of s

More than two billion people and 40% of global agricultural production depend upon unsustainable groundwater extraction. Managed aquifer recharge (MAR), the practice of strategically recharging water to replenish subsurface storage, is an important subbasin scale practice for managing groundwater more sustainably. However, it is not yet reaching its full potential to counterbalance growing global groundwater demand. Agricultural managed aquifer recharge (Ag-MAR) is an emerging method for spreading large volume flows on agricultural lands and has capacity for widespread global implementation. Yet, knowledge gaps, synergies, and tradeoffs in Ag-MAR research still exist. We identify six key system considerations when implementing Ag-MAR: water source, soil and unsaturated zone processes, impact on groundwater, crop system suitability, climate change and impact on greenhouse gas emissions, and social and economic feasibility. We describe the present distribution, need for common terminology, and benefits of Ag-MAR including groundwater storage, increased environmental flows, and domestic wells support. We then outline major gaps, namely, water quality impacts, and crop health and yield. We showcase the multidisciplinary approach needed for communication and coordination of Ag-MAR programs with stakeholders and the public and provide a framework for implementation. Finally, we outline a vision for the path to Ag-MAR implementation. Ag-MAR is an important approach for achieving groundwater sustainability. However, it is one of many necessary solutions and does not offset the need for groundwater conservation.

Airborne Geophysical Method Images Fast Paths for Managed Recharge of California’s Groundwater

Environmental Research Letters (IOP) | November 17th, 2022

Given the substantial groundwater level declines in the Central Valley of California, there is an urgent need to supplement the recharge of the groundwater systems by imp

Given the substantial groundwater level declines in the Central Valley of California, there is an urgent need to supplement the recharge of the groundwater systems by implementing managed aquifer recharge. With approximately 170 km3 (140 million acre-feet) of available groundwater storage space, water deemed to be excess during wet years could be spread on the ground surface at selected locations allowing it to move downward to recharge the underlying aquifer system. Along the eastern edge of the Central Valley there are large paleovalleys that can act as fast paths expediting the downward movement of water. These paleovalleys, incised and then filled with coarse-grained materials – sand, gravel, cobbles – at the end of the last glacial period, are referred to as incised valley fill (IVF) deposits. An IVF deposit has been mapped at one location in the Kings River alluvial fan, with others proposed to exist in the fans of major rivers. If located, these deposits would be optimal sites for managed recharge. In this study, we assessed the use of a helicopter-deployed geophysical method to efficiently locate IVF deposits throughout the Central Valley. We acquired 542 line-kilometers of airborne electromagnetic (AEM) data in the Kings River alluvial fan, with dense line-spacing over the Kings River IVF deposit which had been mapped as ~2 km wide, extending over 20 km into the Central Valley, from the ground surface to a depth of 30 m. The IVF deposit was unambiguously imaged in the AEM data as an extensive linear feature that was more electrically resistive than the surrounding materials due to the high percentage of coarse-grained sediments. This study provides the evidence to support the rapid adoption of the AEM method to locate IVF deposits along the eastern edge of the Central Valley. These deposits provide valuable natural infrastructure for recharging California’s groundwater.

Alamitos Barrier Project: Annual Report on the Control of Seawater Intrusion 2016-2017

Los Angeles County Department of Public Works (LACDPW) | June 30th, 2017

The Alamitos Barrier Project (ABP) was designed and constructed to protect the groundwater supplies of the Central/Orange County Basin of the Coastal Plain

The Alamitos Barrier Project (ABP) was designed and constructed to protect the groundwater supplies of the Central/Orange County Basin of the Coastal Plain from the intrusion of seawater through the Alamitos Gap area. The project facilities are located near the Los Angeles-Orange County border about two miles inland from the terminus of the San Gabriel River. The original facilities included injection wells to form a freshwater pressure ridge and extraction wells to form a saltwater trough. The freshwater pressure ridge has proven to be historically effective, whereas the saltwater trough has not. As a result, the extraction wells are currently not in operation. A map showing the supply pipeline, injection wells, extraction wells, and observation wells is shown on page A-12.1. The County of Los Angeles Department of Public Works (Public Works) operates and maintains the ABP and its associated facilities under the direction and approval of the Joint Management Committee (JMC), acting on behalf of the Los Angeles County Flood Control District (LACFCD) and the Orange County Water District (OCWD). This report summarizes design and construction issues, operation and maintenance activities, hydrogeologic effects, chloride concentrations, and project costs for Fiscal Year (FY) 2016-17 (i.e., July 1, 2016 through June 30, 2017).

Aliso Water District Groundwater Sustainability Plan

Aliso Water District Groundwater Sustainability Agency | January 17th, 2020

Aliso Water District Groundwater Sustainability Plan (Amended)

Aliso Water District Groundwater Sustainability Agency | July 7th, 2022

The January 2020 AWD GSA GSP, along with the other GSPs of the Delta-Mendota Subbasin, was deemed incomplete by DWR January 21, 2022 (Appendix H). The incomplete determin

The January 2020 AWD GSA GSP, along with the other GSPs of the Delta-Mendota Subbasin, was deemed incomplete by DWR January 21, 2022 (Appendix H). The incomplete determination provided 180 days to respond to the deficiencies identified by DWR. Subsequently, multiple consultations with DWR and meetings of the Delta-Mendota GSP groups were held to develop a coordinated response. This GSP, including the Common Chapter (Appendix B), addresses the concerns of DWR’s January 2022 Determination Letter. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5

Amargosa Desert Hydrographic Basin 14-230 Groundwater Pumpage Inventory Water Year 2015

State of Nevada | July 31st, 2015

Ambient noise differential adjoint tomography reveals fluid-bearing rocks near active faults in Los Angeles

Nature Portfolio (Springer Nature) | October 28th, 2023

Amended Groundwater Sustainability Plan, Tri-County Water Authority - Tule Subbasin

Tri-County Water Authority | July 27th, 2022

The Tule Subbasin submitted six GSPs, including one for the Tri-County Water Authority, in January 2020 to the Department of Water Resources (DWR). DWR was required to de

The Tule Subbasin submitted six GSPs, including one for the Tri-County Water Authority, in January 2020 to the Department of Water Resources (DWR). DWR was required to determine whether the GSPs conformed to the specific requirements of SGMA. DWR issued a single determination letter for the Tule Subbasin commenting on all six GSPs. In a letter dated January 28, 2022, DWR determined that that the GSP is incomplete. DWR stated that the GSP was considered incomplete as “it does not define undesirable results or set sustainable management criteria for groundwater levels, subsidence, and water quality in the manner consistent with SGMA and the GSP regulations.” Upon receiving the incomplete determination, the Subbasin had 180 days to address the identified deficiencies and submit revised GSPs by July 27, 2022. The TCWA is submitting this 2022 Amended GSP to address the three deficiencies outlined in the determination letter. Due to size, this file has been divided. Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8, Part 9

Amended Olcese Groundwater Sustainability Plan (GSP) for Certain Lands Overlying the Kern County Subbasin

Olcese Groundwater Sustainability Agency | July 27th, 2022

This GSP has been prepared by the Olcese GSA, which is the GSA for the portion of the Kern County Subbasin of the San Joaquin Valley Groundwater Basin (Department of Wate

This GSP has been prepared by the Olcese GSA, which is the GSA for the portion of the Kern County Subbasin of the San Joaquin Valley Groundwater Basin (Department of Water Resources [DWR] Basin No. 5-022.14, referred to herein as the “Kern Subbasin” or “Basin”) that underlies the Olcese Water District (“OWD” or “District”). The area that is covered by this GSP is referred to herein as the “Olcese Groundwater Sustainability Agency Area” or “Olcese GSA Area” and is located in the eastern portion of the Kern Subbasin. The Kern Subbasin is one of 21 basins and subbasins identified by the DWR as being critically overdrafted, a designation that triggers an accelerated timetable for GSP development by 2020 and achievement of sustainability by 2040. As of June 2022, a total of 14 GSAs, including the Olcese GSA, have been formed within the Kern Subbasin and a total of six GSPs have been prepared by these various GSAs. This Olcese GSP has been developed in coordination with the other GSPs for the Kern Subbasin to meet SGMA regulatory requirements1 while reflecting the unique hydrogeologic conditions within the Olcese GSA Area and preserving local control over water resources. Pursuant to the SGMA GSP submittal deadline, the Olcese GSP was originally submitted to DWR in January 2020; this amended Olcese GSP is in response to DWR’s 28 January 2022 letter entitled Incomplete Determination of the 2020 Groundwater Sustainability Plans Submitted for the San Joaquin Valley – Kern County Subbasin. Together, the Kern Subbasin GSPs provide a path to maintain the long-term sustainability of locally managed groundwater resources now and into the future. Due to size, this file has been divided. Part 1, Part 2

An Evaluation of California’s Adjudicated Groundwater Basins

University of California, Santa Cruz (UC Santa Cruz) | October 1st, 2016

Groundwater is a critical resource in California, providing on average 30 percent of the state’s total water supply and significantly more during dry years. Many commu

Groundwater is a critical resource in California, providing on average 30 percent of the state’s total water supply and significantly more during dry years. Many communities rely exclusively on groundwater, and it is an essential back-up source of water during droughts when pumping increases significantly to compensate for reduced surface supplies. Local groundwater management agencies, special act districts, and court adjudications are the primary institutional arrangements to manage groundwater in California. Increasing groundwater declines in many areas of the state and concomitant negative impacts prompted the passage of the 2014 Sustainable Groundwater Management Act (SGMA). The SGMA established new requirements for 127 high- and medium-priority groundwater basins that are either in overdraft or vulnerable to overdraft to develop sustainable management programs with increased state oversight. The SGMA defines sustainable groundwater management as: “The management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results.” Undesirable results include: chronic lowering of groundwater levels; significant and unreasonable reduction of groundwater storage; significant and unreasonable seawater intrusion, degraded water quality, and land subsidence; depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water. The SGMA exempts 388 basins categorized as low- and very-low priority, as well as all the adjudicated groundwater basins and 3 basins with pending groundwater adjudications. The SGMA was followed by the passage of Assembly Bill 1390 (AB 1390) and Senate Bill 226 (SB 226) in 2015 that provide some procedures for groundwater adjudications. In the adjudication of a groundwater basin, the court generally defines and determines water rights for all users and provides court-supervised basin management by a Watermaster, who is usually appointed by the court to ensure that the basin is managed in accordance with the court’s decree. Prior to adjudication, key stakeholders and users of the groundwater in a basin often negotiate a stipulation and physical solution to manage the basin, and the court can then accept it in whole or in part, or reject it and craft a different solution to manage the basin. There is limited analysis of the history and current condition of California’s adjudicated basins and the potential for future improvements to the adjudication process. This report for the State Water Resources Control Board (SWRCB) evaluates all of California’s adjudicated basins with respect to sustainable groundwater management as defined in SGMA including: accomplishments, challenges, how management can be improved, and whether there are common elements that result in the sustainable management of an adjudicated groundwater basin.