Groundwater Recharge

Photo: Department of Water Resources

For basins that are critically overdrafted and many others, sustainable management while maintaining current acreage in production means finding a way to replenish their basins.   Groundwater recharge is an important component of sustainable groundwater management, as increasing the amount of recharge can help improve conditions in overdrafted basins, or allow for additional pumping in basins that are not experiencing chronic declines in groundwater levels.

Water for groundwater recharge projects can come from many different sources, such as surface water, stormwater runoff, recycled water, or remediated groundwater. Geology permitting, this can then be recharged into the aquifer by way of percolation basins, canals, natural drainages, injection wells, or conjunctive use.

The idea of using groundwater aquifers to manage and store water below ground is certainly not new; programs for managed recharge of groundwater aquifers have been in place for decades in Orange County, Santa Clara Valley, Kern County, and many other regions in the state. It is an important tool for sustainable groundwater management and recovery from groundwater depletion. The ability in wet times to store water underground in dry years is central to the ability to conjunctively manage groundwater and surface water supplies.

Groundwater recharge projects that can also provide multiple benefits, such as maintaining agricultural productivity or domestic water use, sustaining groundwater-dependent ecosystems (GDEs), and providing water for wintering shorebirds and fisheries.  Plus, multi-benefit projects can facilitate multiple streams of funding to implement multi-benefit recharge projects.

Key publications

A Technical Framework for Increasing Groundwater ReplenishmentReplenishing Groundwater in the San Joaquin ValleyManaged Aquifer Recharge and the U.S. Army Corps of Engineers: Water Security through ResilienceBuilding multi-benefit recharge basinsGuide to on-farm recharge and waterbird habitatMulti-benefit groundwater recharge case studies

A Technical Framework for Increasing Groundwater Replenishment

A Technical Framework for Increasing Groundwater Replenishment is a roadmap document for local agencies or groundwater sustainability agencies (GSAs) to utilize when navigating how to develop groundwater replenishment projects.

This document walks readers through the current landscape of the Sustainable Groundwater Management Act (SGMA) and provides the context that, as part of SGMA implementation, groundwater replenishment will be an important component to how sustainability is achieved under SGMA.

The technical framework provides considerations for how to develop groundwater replenishment projects and includes additional resources that support the development of groundwater replenishment projects, as well as case studies of entities that are piloting their own replenishment projects.

Click here to download A Technical Framework for Increasing Groundwater Replenishment from ACWA.

Replenishing Groundwater in the San Joaquin Valley

The San Joaquin Valley—which has the biggest imbalance between groundwater pumping and replenishment in the state—is ground zero for implementing the 2014 Sustainable Groundwater Management Act (SGMA). Expanding groundwater recharge could help local water users bring their basins into balance and make a dent in the long-term deficit of nearly 2 million acre-feet per year.

The experience with recharge in 2017―the first wet year since the enactment of SGMA―offers valuable insights in how to expand recharge. A survey of valley water districts’ current recharge efforts revealed strong interest in the practice, and a number of constraints.

Click here to download this report from the Public Policy Institute of California.

Managed Aquifer Recharge and the U.S. Army Corps of Engineers: Water Security through Resilience

Storing water underground (managed aquifer recharge, or MAR) can augment surface storage and increase resilience of USACE projects and improve our nation’s water security. USACE and its partners are using, have considered or are considering using MAR, or conjunctive management of ground- and surface water, in at least 17 states in six of the seven USACE divisions in the Continental United States.

The authorities for using MAR in USACE projects are modest but increasing.USACE is using or considering MAR to help fulfill its primary missions of flood risk management and aquatic ecosystem restoration, and for secondary purposes such as drought resilience, water supply, and reducing saltwater intrusion. For secondary mission areas, the agency’s role in MAR is typically to support its partners’ efforts to meet their water resources needs.

MAR can be smoothly integrated into USACE’s planning process, including stakeholder engagement, reallocation studies and forecast-informed reservoir operations.

Click here to read this article.

Building multi-benefit recharge basins

As California faces an unpredictable water future, policy makers and water managers across the state are seeking solutions to build resilience into our water supply system. Groundwater recharge is an excellent tool to replenish depleted aquifers and bank water for future use.

In addition to helping water managers balance their water budget, groundwater recharge also provides an opportunity to create habitat for wildlife.

This guide highlights recharge basin management strategies that create wildlife habitat and provide operational benefits to basin managers

Building multi-benefit recharge basins

Guide to on-farm recharge and waterbird habitat

With the Sustainable Groundwater Management Act (SGMA) requiring basins to balance water budgets and manage groundwater sustainably, there is an opportunity to demonstrate groundwater recharge with benefits to birds and people.

A multiple-benefit approach brings together water managers, farmers, agencies and conservation groups to stabilize groundwater in a manner that provides greater water reliability for farms and communities while protecting ecosystems, including migratory bird habitat.

Guide to On-farm Recharge and Waterbird Habitat

Multi-benefit groundwater recharge case studies

Groundwater recharge will be an important tool for GSAs to use for achieving long-term groundwater sustainability. Recharging aquifers is important for multiple purposes including agricultural productivity, domestic water use, and providing water for GDEs.

These case studies show how managed aquifer recharge projects can also provide benefits to nature, including providing water for wintering shorebirds, fisheries, and other GDEs such as riparian habitats. These examples show how to facilitate multiple streams of funding to implement these multi-benefit recharge projects.

Multi-Benefit Groundwater Recharge Case Studies


Water Available for Replenishment Report

A critical element of sustainable groundwater management is the replenishment of groundwater basins. SGMA directs the California Department of Water Resources (DWR) to provide assistance to local agencies in estimating the amount of water available for groundwater replenishment. The act directs DWR to prepare a report “that presents the department’s best estimate, based on available information, of water available for replenishment of groundwater in the state” (California Water Code Section 10729(c)).

DWR has developed planning estimates of surface water available for replenishment (referred to in this report as WAFR estimates) for each of the state’s 10 hydrologic regions and 56 planning areas. These estimates and the related water resources information are presented in this report.

Managed Aquifer Recharge (MAR)

Managed aquifer recharge (MAR), also known as water banking, consists of water management methods that recharge an aquifer using either surface or underground recharge techniques. The stored water is available for use in dry years when surface water supplies may be low.

Click here for more information on Managed Aquifer Recharge.

Aquifers, the porous rocks and sediments that hold and transmit groundwater, are naturally replenished by surface water that seeps into the ground. MAR enhances the recharge rate by creating artificial streams and ponds where water trickles into the ground, or by using wells to directly inject water underground. MAR can also be used to improve groundwater quality and prevent some of the negative consequences of groundwater depletion, like ground sinking (subsidence) or the intrusion of salty groundwater from the oceans into coastal freshwater aquifers.

Because of its arid climate and large population, California is home to some of the oldest and largest MAR projects in the United States. This case study highlights four of these projects, covering almost a century of MAR and water security in California.

Click here for a factsheet on Managed Aquifer Recharge.

​Flood-Managed Aquifer Recharge (Flood-MAR)

“Flood-MAR” is an integrated and voluntary resource management strategy that uses flood water resulting from, or in anticipation of, rainfall or snow melt for managed aquifer recharge (MAR) on agricultural lands and working landscapes, including but not limited to refuges, floodplains, and flood bypasses.

Flood-MAR can be implemented at multiple scales, from individual landowners diverting flood water with existing infrastructure, to using extensive detention/recharge areas and modernizing flood management infrastructure/operations.

Learn more about Flood-MAR at the DWR webpage.

Click here to watch a video on Flood MAR.

With the effects of climate change necessitating wholesale changes in how water is managed in California, “Flood-MAR” presents a sustainable strategy that can simultaneously accommodate longer and deeper droughts, and more severe and frequent episodic and seasonal flooding. Flood-MAR is an integrated water resource management strategy that uses flood water resulting from, or in anticipation of, rainfall or snowmelt for managed aquifer recharge on agricultural lands and working landscapes. Flood-MAR can also be implemented at multiple scales, from individual landowners diverting flood water with existing infrastructure to using extensive detention/recharge areas and modernizing flood management infrastructure and operations.

Click here to view/download the report, FLOOD- MAR: Using Flood Water for Managed Aquifer Recharge to Support Sustainable Water Resources

​Groundwater Recharge Assessment Tool (GRAT)

Sustainable Conservation’s Groundwater Recharge Assessment Tool (GRAT)  provides irrigation districts and GSAs with a decision support tool that will enable them to easily create and assess recharge scenarios.  ]

The GRAT tool enables water managers to evaluate where (active cropland, fallow land, and dedicated recharge basins), when (which weeks across multiple water year types, across a 20-year planning horizon) and how much water will be recharged based on best available data and hydrologic, agronomic and geologic science. It enables GSA’s to see their most cost-effective options and consider the unintended environmental and social impacts in their basins.

Click here for more on the Groundwater Recharge Assessment Tool (GRAT)

​Sustainable Conservation’s GRAT tool allows you to identify and prioritize the most cost-effective on-farm recharge projects and operations.

Recharge Net Metering

A key challenge for developing distributed groundwater recharge projects lies in creating incentives that will motivate landowners, tenants, and other stakeholders to participate.  Recharge Net Metering (ReNeM) is a strategy derived from a renewable energy incentive known as Net Energy Metering which encourages the adoption of rooftop solar panels.

Click here to learn more about Recharge Net Metering.

Recharge Net Metering incentivizes groundwater recharge by offsetting costs incurred by landowners for operation and maintenance of water collection and infiltration systems that are placed on their land.

ReNeM participants benefit directly through the rebate program; they also benefit indirectly (along with other resource users and regional aquatic systems) because groundwater recharge helps to improve and sustain the supply and quality of groundwater.

Learn more in this issue brief from Berkeley’s Center for Law, Energy & the Environment: Recharge Net Metering to Enhance Groundwater Sustainability

Groundwater Recharge and Water Quality

Groundwater recharge by natural or artificial means can cause changes in groundwater quality. These changes will depend on many factors, including the chemistry of the source water, land use, soil and sediment characteristics, the groundwater flow dynamics. The potential for water-quality changes should be evaluated before, during, and after implementation of an artificial recharge program.

Click here to learn more about groundwater recharge and groundwater quality.

From the late 1940s through 1994, water levels in the Warren subbasin declined as much as 300 ft. due to groundwater extraction. In response, the Hi-Desert Water District (HDWD) instituted an artificial recharge program to replenish the groundwater basin using imported California State Water Project (SWP) water. The program resulted in water-level recovery of about 250 ft. between 1995 and 2003. However, nitrate concentrations in some wells also increased to levels above the USEPA maximum contaminant level. The USGS concluded that septage from septic tanks was the primary source of nitrate to the groundwater system.

Learn more about water quality considerations during groundwater recharge:

Sourced from the USGS website, 9/5/2020.

Water rights and permit information

Depending upon the parameters of the recharge project, you may or may not need to obtain a water right or other permit from the State Water Board.  Generally, capturing and storing surface water generally requires an appropriative water right.  Parties can obtain new water rights or change existing water rights to authorize groundwater recharge projects.

For parties obtaining new water rights, there are different water right applications that are available for groundwater recharge: standard and temporary. The type of application needed depends on the project operation length, intended use, and urgency.

Standard water rights are ideal for long term projects. Temporary permits are best for short term diversions. However, temporary permits are not water rights, but rather they are a conditional approval to divert and use available water that has not been claimed by a water right holder.

Click here for the groundwater recharge permitting page at the State Water Board.

Click here for a fact sheet on Flood Control, Groundwater Recharge, and Water Rights.
Click here for a fact sheet on Purposes of Use for Underground Storage Projects.
Click here to view/download for a FAQ on general groundwater recharge permitting.
Click here to view/download for a FAQ on streamlined permitting and eligibility for groundwater recharge projects.
Click here to view/download for a FAQ on groundwater recharge technical considerations.

Protection of Groundwater Recharge Areas

Recharge areas are those areas that provide the primary means of replenishing groundwater.  Good natural recharge areas are those where good quality surface water is able to percolate through the sediments and rocks to the saturated zone which contains groundwater. If recharge areas cease to function properly, it will limit groundwater replenishment and/or groundwater quality for storage or use.

Protection of recharge areas requires a number of actions based on two primary goals: (1) ensuring that areas suitable for recharge continue to be capable of adequate recharge rather than being covered by urban infrastructure, such as buildings and roads, and (2) preventing pollutants from entering groundwater to avoid expensive treatment that may be necessary prior to beneficial use.

Click here to view/download DWR's Resource Management Strategy for Recharge Area Protection.
Click here for the State Water Board's map of hydrologically vulnerable areas.


Groundwater recharge articles at Maven’s Notebook

  • Notebook groundwater recharge posts

Explore groundwater recharge at the California Water Library



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