Reference Guide to On-Farm Groundwater Recharge on Annual Cropland | Recommendations for Creating Waterbird Habitat Benefits

Nature Conservancy | May 1st, 2019

With the Sustainable Groundwater Management Act (SGMA) requiring basins to balance water budgets and manage groundwater sustainably, there is an opportunity to demonstr

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.

Replenishing Groundwater in the San Joaquin Valley

Public Policy Institute of California (PPIC) | April 1st, 2018

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

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. The following actions are needed to better capitalize on future opportunities: Clarify rules on water available for recharge. The State Water Board needs to develop an expeditious process for enabling water users to capture surface water when it is available. Beyond the legal aspects of establishing rights for diversion and storage, an essential part of this process is technical: developing a simple, rapid way to determine when river flows exceed water required for environmental purposes and downstream users. Evaluate infrastructure capacity. One of the key challenges for expanding recharge is that most available flows are in the northern part of the valley, while most of the overdraft?and best recharge lands?are in the south. In addition, these flows are mainly available for just a few months. A top priority is to evaluate opportunities for improving the use of existing infrastructure (conveyance facilities, surface reservoirs, and recharge basins) and determine where additional investments are warranted. A big bottleneck is likely to be regional conveyance, which is inadequate for capturing and moving high flows to suitable recharge locations. Improve recharge on farmland. Active recharge on farmland may be one of the most promising ways to capture water cost-effectively in wetter years, but it is low relative to its potential. Significantly ramping up this practice will require addressing a suite of technical issues and establishing incentives. Address regulatory barriers. State and federal agencies need to improve processes for approving construction of new recharge projects, moving recharge water through their conveyance facilities, and enabling more flexibility in where water is stored. Water managers and growers also need guidelines from the state for implementing on-farm recharge in ways that are consistent with water quality rules. Strengthen groundwater accounting. Better accounting of water going into and out of groundwater basins is key to sustainable management. It is also needed for developing incentives for growers to recharge, encouraging recharge partnerships, and informing decisions on new investments. Making the most of recharge opportunities will require high levels of cooperation among a wide variety of stakeholders. Local and regional partnerships?for capturing and moving water efficiently, making new investments, and devising projects that bring multiple benefits?are key to helping the region manage this critical resource over the long-term.

Replenishing Groundwater in the San Joaquin Valley: 2024 Update

Public Policy Institute of California (PPIC) | June 6th, 2024

Strategies to replenish groundwater basins—long used in some areas of the San Joaquin Valley—have increasingly come into focus as the region seeks to bring its overd

Strategies to replenish groundwater basins—long used in some areas of the San Joaquin Valley—have increasingly come into focus as the region seeks to bring its overdrafted groundwater basins into balance under the Sustainable Groundwater Management Act (SGMA). In late 2023, following a very wet winter and spring, we conducted a repeat survey of local water agencies about their recharge activities and perspectives, building on a similar survey at the end of 2017, a year with similar levels of precipitation. We found signs of progress on recharge since 2017, as well as areas where more work is needed to take full advantage of this important water management tool.

Report of Waste Discharge and Technical Report

Westlands Water District | July 10th, 2019

This Technical Report is in support of a Report of Waste Discharge (ROWD) for an agricultural aquifer storage and recovery (Ag-ASR) program for Westlands Water District

This Technical Report is in support of a Report of Waste Discharge (ROWD) for an agricultural aquifer storage and recovery (Ag-ASR) program for Westlands Water District (Westlands or District). The District is located in western Fresno and Kings Counties in the San Joaquin Valley. With the new Sustainable Groundwater Management Act (SGMA) signed into law in 2014, Westlands is pursuing means to recharge groundwater within the District’s boundaries, which coincide with the Westside Subbasin (Groundwater Subbasin Number 5-22.09). Due to the presence of poor quality shallow groundwater, fine-grained soils, and the Corcoran Clay restrictive layer, surface recharge opportunities are limited (Schmidt, 2009). Direct injection using Ag-ASR wells holds promise as a more widely implementable recharge method in the District.

Resistivity imaging reveals complex pattern of saltwater intrusion along Monterey coast

Journal of Hydrology (Elsevier) | February 22nd, 2017

A coastal region represents a dynamic zone where fresh groundwater in the coastal aquifers interacts with saline ocean water. The location of the freshwater-saltwater int

A coastal region represents a dynamic zone where fresh groundwater in the coastal aquifers interacts with saline ocean water. The location of the freshwater-saltwater interface is governed by the density and pressure differences on the two sides of the interface and the subsurface hydrologic properties that control fluid movement. Saltwater intrusion is the process in which this interface moves landward, with saltwater then occupying parts of the aquifer that were once fresh. While this process has been observed and documented throughout the world for over a century (Bear et al., 1999), climate change, growing water demands, and manipulation of natural hydrologic systems have led to saltwater intrusion being considered a significant threat to future freshwater resources globally (Kinzelbach et al., 2003; Barlow and Reichard, 2009; Werner et al., 2013). Saltwater intrusion can have a number of significant economic and environmental impacts, including diminished freshwater storage capacity, contamination of freshwater production wells, soil salinization, and decreased nutrient laden freshwater discharge to marine ecosystems (Johannes, 1980; Taniguchi et al., 2002; Werner et al., 2013). A number of steps can be taken to attempt to slow the rate of saltwater intrusion, including spatial and temporal changes in the extent of groundwater pumping, in landuse, in surface water diversions, and in artificial recharge (Abarca et al., 2006). What is needed however is a way to prioritize these actions, or combinations of actions, so as to optimize the impact on saltwater intrusion. This requires an accurate understanding of the current distribution of freshwater and saltwater, that can be used to predict future locations in response to these, and other, actions (Sanford and Pope, 2009). Saltwater intrusion is traditionally mapped and monitored using measurements made in wells and predictive flow models (Werner et al., 2013). There are a number of limitations with these methods. Measurements made in wells provide point data, which may fail to capture the spatial complexity in subsurface conditions. Improving spatial coverage with additional wells can be cost prohibitive (Ogilvy et al., 2009). Additionally, salinity measurements from wells can be flux-averaged concentrations, and head measurements in wells are affected by the density of the water column so can be misinterpreted in the presence of unknown salt water, and are susceptible to measurement, instrument, and time lag errors (Carrera et al., 2009; Post and Von Asmuth, 2013). Models are generally calibrated by matching historic head values in wells and/or matching salinity values from well samples (Carrera et al., 2009), thus all the limitations of well data are carried over into the model calibration. Given these limitations there is significant opportunity for additional methods of mapping and monitoring the distribution of saltwater in the subsurface for improved management of coastal aquifers.

Revised Groundwater Sustainability Plan County of Fresno GSA Management Area A & Management Area B Delta-Mendota Subbasin

County of Fresno | July 20th, 2022

The Delta-Mendota Subbasin (Basin 5-022.07 in the California Department of Water Resources (DWR) Bulletin 118) (Subbasin) is a high priority Subbasin that has been assign

The Delta-Mendota Subbasin (Basin 5-022.07 in the California Department of Water Resources (DWR) Bulletin 118) (Subbasin) is a high priority Subbasin that has been assigned a critical overdraft designation by DWR. The Subbasin consists of 24 Groundwater Sustainability Agencies (GSA) who together created six individual GSA groups, each preparing a GSP in a coordinated manner as required by SGMA. The County of Fresno elected to serve as the GSA for County areas within the Subbasin that are not included in other GSAs. The GSP group consists of two individual GSA’s Management Area A (MAA) and Management Area B (MAB) and are collectively referred to as Fresno County Management Areas (FCMA).

Rivers that Depend on Aquifers: Drafting SGMA Groundwater Plans with Fisheries in Mind

Golden Gate University (GSU) | April 12th, 2018

In California, surface waters have historically been regulated as if they were unconnected to groundwater. Yet, in reality, surface waters and groundwater are often hydro

In California, surface waters have historically been regulated as if they were unconnected to groundwater. Yet, in reality, surface waters and groundwater are often hydrologically connected. Many of the rivers that support fisheries such as salmon and trout are hydrologically dependent on tributary groundwater to maintain instream flow. This means that when there is intensive pumping of tributary groundwater the result can be reductions in instream flow and damage to fisheries. For this reason, stakeholders concerned about adequate instream flows for fisheries in California’s rivers, streams and creeks need to be effectively engaged in the implementation of California’s Sustainable Groundwater Management Act (SGMA). Consider the Scott River in Northern California, part of the larger Klamath River Basin. Nearby groundwater contributes to the Scott River. When high volumes of groundwater are extracted from nearby wells, it depletes the Scott River’s instream flow with adverse impacts on salmon and steelhead trout. As discussed further in Section VI of this guidebook, this has led to litigation over the application of California public trust law to groundwater extraction affecting Scott River instream flows, and efforts to use SGMA to ensure that groundwater pumping near the Scott River is compatible with the instream flow needs of fisheries. Situations similar to the Scott River surface and groundwater basin are unfolding throughout California. On a statewide basis, how pervasive is the effect of groundwater pumping on surface water flows? Research by Maurice Hall of the Environmental Defense Fund, utilizing the California Department of Water Resources Central Valley Groundwater Surface Flow Model, provides us with some sense of the magnitude of the problem. In a May 2018 presentation, Hall reported: What the model showed us is that early in the 1900s, 1940s and 1950s, the Sacramento River received a net inflow from the groundwater of something like 1 million acre feet a year…Since that time, the groundwater levels have gone down, and the amount of water that has flowed into the Sacramento River from the surrounding groundwater has gone down accordingly to the point that when we were doing this modeling around 2010, it appeared that on average, the Sacramento River lost just about as much as it gained from the surrounding groundwater in the valley floor. This is the Sacramento River and all of its tributaries upstream of the Sacramento…So the net effect over that period is there was roughly on average 900,000 acre-feet per year less water showing up in the  Sacramento River at Sacramento.” (Hall and O’Brien). SGMA was enacted in 2014. Pursuant to SGMA, by June 2017 a groundwater sustainability agency was required to be designated for each groundwater basin in California. Each groundwater sustainability agency in high and medium priority basins must prepare and adopt a Groundwater Sustainability Plan (SGMA Groundwater Plan) by 2020 if the basin is deemed to be in a critical state of overdraft or 2022 for all remaining high and medium priority basins. Each SGMA Groundwater Plan must detail how the groundwater basin will be managed to avoid overdraft conditions and, importantly for fisheries, to avoid adverse impacts on hydrologically connected surface waters. Although groundwater sustainability agencies and fishery stakeholders recognize that the groundwater-surface water connection needs to be addressed in SGMA Groundwater Plans, at present there is limited guidance on how to do this. That is, what are the specific types of information, modeling, monitoring, and pumping provisions that should be included in SGMA Groundwater Plans to ensure that groundwater extraction does not cause significant adverse impacts on fisheries? The purpose of this guidebook is to provide such guidance.

Root Creek Water District Groundwater Sustainability Agency Groundwater Sustainability Plan

Root Creek Water District | November 11th, 2019

Root Creek Water District Groundwater Sustainability Plan

Root Creek Water District | March 20th, 2023

Root Creek Water District Groundwater Sustainability Plan

Root Creek Water District | November 11th, 2019

The RCWDGSA covers almost 10,000 acres in southeast Madera County located southwest of the intersection of State Highway 41 and Avenue 12 along the banks of and just nort

The RCWDGSA covers almost 10,000 acres in southeast Madera County located southwest of the intersection of State Highway 41 and Avenue 12 along the banks of and just north of the San Joaquin River. In size, the GSA accounts for less than 3 percent of the land area within the Madera Basin. The District, which lies wholly within the GSA has recently contracted for surface water supplies from the Madera Irrigation District (MID) and the Wonderful Nut Orchards for up to 17,000 acre-feet (af) of surface water in a given year. The District has also recently completed the first phase of an agricultural conveyance and distribution system that has the ability to deliver surface water to approximately 2,500 acres of farmland. Since its completion, the system has delivered approximately 16,382af of surface water to date in the past three years.To accomplish these achievements the district has invested more than 12 million dollars. While large, the purchase and delivery of surface water supplies are crucial to the long-term groundwater sustainability of not only the District and the GSAbut also the region and the subbasin.