BasinScout: Water Quantity

Freshwater Trust | January 16th, 2018

California’s Sustainable Groundwater Management Act (SGMA) establishes milestones that high- and medium-priority basins in a critical state of overdraft must meet to be

California’s Sustainable Groundwater Management Act (SGMA) establishes milestones that high- and medium-priority basins in a critical state of overdraft must meet to become sustainable. BasinScout can assist managers in building an objective allocation plan that reflects the needs of various stakeholders in shaping how sustainability is achieved.

Bay Area Green Infrastructure Water Quality Synthesis

San Francisco Estuary Institute (SFEI) | June 1st, 2018

San Francisco Bay is impacted by the numerous urban pollutants that flow from the surrounding landscape during storm events. In San Francisco Bay, total maximum daily lo

San Francisco Bay is impacted by the numerous urban pollutants that flow from the surrounding landscape during storm events. In San Francisco Bay, total maximum daily load (TMDL) clean-up plans are in place for polychlorinated biphenyls (PCBs) and mercury (Hg) (Davis et al., 2007; Davis et al., 2012). As municipalities strive to reach regulatory targets, green infrastructure (GI) presents a promising solution for managing stormwater pollutants while achieving additional environmental and social benefits. However, remaining data gaps including the best design layout, media composition, and vegetation and submerged zone effects on performance can prevent local managers from accurately assessing water quality benefits provided by green infrastructure as well as the maintenance needs to sustain adequate performance.

Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers

American Geophysical Union (AGU) | July 31st, 2016

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less tha

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less than 150 m deep) in agricultural areas are often contaminated by nitrate. Agricultural and rural nitrate sources include dairy manure, synthetic fertilizers, and septic waste. Knowledge of the relative proportion that each of these sources contributes to nitrate concentration in individual wells can aid future regulatory and land management decisions. We show that nitrogen and oxygen isotopes of nitrate, boron isotopes, and iodine concentrations are a useful, novel combination of groundwater tracers to differentiate between manure, fertilizers, septic waste, and natural sources of nitrate. Furthermore, in this work, we develop a new Bayesian mixing model in which these isotopic and elemental tracers were used to estimate the probability distribution of the fractional contributions of manure, fertilizers, septic waste, and natural sources to the nitrate concentration found in an individual well. The approach was applied to 56 nitrate-impacted private domestic wells located in the San Joaquin Valley. Model analysis found that some domestic wells were clearly dominated by the manure source and suggests evidence for majority contributions from either the septic or fertilizer source for other wells. But, predictions of fractional contributions for septic and fertilizer sources were often of similar magnitude, perhaps because modeled uncertainty about the fraction of each was large. For validation of the Bayesian model, fractional estimates were compared to surrounding land use and estimated source contributions were broadly consistent with nearby land use types.

Beale Air Force Base Environmental Cleanup Program Issue 67

U.S. Air Force | October 31st, 2015

Bear Valley Basin Groundwater Sustainability Plan

Bear Valley Basin Groundwater Sustainability Agency | June 15th, 2022

The GSP provides the geographical and managerial context of the Bear Valley Basin, summarizes the groundwater basin setting (including groundwater conditions, water budge

The GSP provides the geographical and managerial context of the Bear Valley Basin, summarizes the groundwater basin setting (including groundwater conditions, water budget, and management areas), describes the criteria used to measure and demonstrate sustainability, reviews the existing groundwater monitoring and management programs, and defines how those actions will be incorporated into the Bear Valley Basin GSP to achieve and maintain sustainability in the future.

Beneath the Surface

Environmental Defense Fund (EDF) | November 1st, 2020

In a state where water is a limited and vital resource, it is imperative to wade into the difficult issues associated with groundwater management in Texas. More specifica

In a state where water is a limited and vital resource, it is imperative to wade into the difficult issues associated with groundwater management in Texas. More specifically, this report, with the input of a diverse group of experienced professionals, provides an overview of the groundwater landscape in Texas, describing some of its key features, and then identifying five of the most important challenges to holistic, proactive groundwater management for Texas.  To set the stage for the groundwater scenario, we list and briefly discuss some key features of Texas groundwater: 1) it is private property; 2) it is primarily managed by groundwater conservation districts; 3) its levels are declining; 4) its legal regime is not the same as the laws governing surface water; 5) it is viewed as an extractable and transferable resource; and 6) its current management framework is challenged. These aspects of Texas groundwater raise interesting and often difficult questions at many levels, in a wide range of settings, from a wide range of perspectives. Landowners; companies in search of a water supply for various purposes; water utilities; private well owners; groundwater conservation districts; river authorities; regional water planning groups; agricultural irrigators; conservation interests; municipal and industrial water suppliers and users; state agencies; government officials; policy makers; legislators; and many others are looking for answers to the questions that persist for Texas groundwater – the source of about 60% of the state’s annual water use.  This document presents five of the major challenges to groundwater management in Texas that have been identified for further consideration and review, then briefly describes each of the five issues presented. Along with background information, the document sets out various perspectives on the issue, provides information on recent or pending litigation, and presents information on the handling of the issue in past sessions of the Texas Legislature.  The first issue presented discusses the challenges related to regulating privately owned, yet shared, groundwater. In the 2012 case Edwards Aquifer Authority v. Day (“Day”), the Texas Supreme Court held that landowners own their groundwater in place.1 The Supreme Court described how one purpose of groundwater regulation, similar to oil and gas, is to afford a landowner his fair share of the groundwater beneath his property. But the court also stated that landowners are subject to reasonable regulation by Groundwater Conservation Districts (GCDs). The legal uncertainty over what “fair share” and “reasonable regulation” mean is upending current groundwater regulation as the districts struggle to allocate groundwater resources under this relatively new holding.  Next, the document discusses the challenges related to groundwater management at the GCD level. GCD critics argue that it is difficult for GCDs to effectively manage groundwater in a fragmented regulatory structure. Proponents of local management of groundwater, however, argue that local control ensures representation of community values and concerns and recognition of hydrogeologic conditions specific to a district’s jurisdiction. The reality is that it can be challenging for GCDs to manage groundwater with actual and threatened litigation increasing and without sufficient funding and science to support their responsibilities under the Water Code.  Third, the challenges associated with groundwater and surface water interactions are presented. Despite the hydrogeological relationship between groundwater and surface water in some areas of the state, Texas water law and policy are often implemented in a fashion that fails to adequately recognize this connection. The absence of a framework for conjunctively managing groundwater and surface water may adversely affect both groundwater and surface water resources.  Fourth, the document describes the challenges related to sustainable management of groundwater. Texas groundwater statutes set the guiding terms for how local GCDs and groundwater management areas (GMAs) set management goals. Recent changes to those laws, and ongoing disputes about how much groundwater can or should be removed from an aquifer, have arguably moved the law away from sustainable management goals and toward maximizing groundwater withdrawals.  Next, there is a discussion of the challenges associated with the marketing and exporting of groundwater. With growing populations, some utilities and cities in search of additional water supplies are turning to importing groundwater from rural areas of Texas. The existing and proposed large-scale marketing and export of groundwater is generating a variety of conflicts, pitting rural interests against urban, potentially threatening the economies, property rights, and ecology of rural areas from where groundwater is exported, and creating regulatory and political challenges for local GCDs.  Finally, there is a brief discussion of a number of additional issues related to groundwater management in Texas, such as aquifer storage and recovery, brackish groundwater desalination, abandoned wells, and transboundary aquifers. 

Benefits and Economic Costs of Managed Aquifer Recharge in California

University of California, Davis (UC Davis) | July 14th, 2016

Groundwater management is important and challenging, and nowhere is this more evident than in California. Managed aquifer recharge (MAR) projects can play an important ro

Groundwater management is important and challenging, and nowhere is this more evident than in California. Managed aquifer recharge (MAR) projects can play an important role in ensuring California manages its groundwater sustainably. Although the benefits and economic costs of surface water storage have been researched extensively, the benefits and economic costs of MAR have been little researched. Historical groundwater data are sparse or proprietary within the state, often impairing groundwater analyses. General obligation bonds from ballot propositions offer a strategic means of mining information about MAR projects, because the information is available publicly. We used bond-funding applications to identify anticipated MAR project benefits and proposed economic costs. We then compared these costs with actual project costs collected from a survey, and identified factors that promote or limit MAR. Our analysis indicates that the median proposed economic cost for MAR projects in California is $410 per acre-foot per year ($0.33 per m3 per year). Increasing Water Supply, Conjunctive Use, and Flood Protection are the most common benefits reported. Additionally, the survey indicates that (1) there are many reported reasons for differences between proposed and actual costs ($US 2015) and (2) there is one primary reason for differences between proposed recharge volumes and actual recharge volumes (AFY): availability of source water for recharge. Although there are differences between proposed and actual costs per recharge volume ($US 2015/AFY), the ranges for proposed costs per recharge volume and actual costs per recharge volume for the projects surveyed generally agree. The two most important contributions to the success of a MAR project are Financial Support and Good Communication with Stakeholders.

Best Management Practices for Sustainable Management of Groundwater: Monitoring Networks and Identification of Data Gaps

California Department of Water Resources (DWR) | December 12th, 2016

The objective of this Best Management Practice (BMP) is to assist in the development of Monitoring Networks and Identification of Data Gaps. The California Department of

The objective of this Best Management Practice (BMP) is to assist in the development of Monitoring Networks and Identification of Data Gaps. The California Department of Water Resources (the Department or DWR) has developed this document as part of the obligation in the Technical Assistance chapter (Chapter 7) of the Sustainable Groundwater Management Act (SGMA) to support the long-term sustainability of California’s groundwater basins. Information provided in this BMP provides technical assistance to Groundwater Sustainability Agencies (GSAs) and other stakeholders to aid in the development of a monitoring network that is capable of providing sustainability indicator data of sufficient accuracy and quantity to demonstrate that the basin is being sustainably managed. In addition, this BMP is intended to provide information on how to identify and plan to resolve data gaps to reduce uncertainty that may be necessary to improve the ability of the GSP to achieve the sustainability goal for the basin.

Best Management Practices of the Sustainable Management of Groundwater Land Subsidence

California Department of Water Resources (DWR) | January 21st, 2026

The Subsidence Best Management Practices document (Subsidence BMP) provides a guide on the fundamentals of land surface subsidence (also called “land subsidence” or �

The Subsidence Best Management Practices document (Subsidence BMP) provides a guide on the fundamentals of land surface subsidence (also called “land subsidence” or “subsidence”), technical assistance related to subsidence, and best practices for managing subsidence. The Subsidence BMP also provides specific information about subsidence in California and how it must be considered within the structure of the Sustainable Groundwater Management Act (SGMA). Subsidence is one of the six sustainability indicators required to be managed under SGMA. The Subsidence BMP does not supersede or replace any existing local, state, or federal regulations. Rather, it is meant to help groundwater managers, especially Groundwater Sustainability Agencies and the public, better understand land subsidence and how it can be managed.

Best Management Practices of the Sustainable Management of Groundwater: Land Subsidence (Draft)

California Department of Water Resources (DWR) | July 23rd, 2025

For almost a century, parts of California have been gradually sinking, impacting critical infrastructure and the communities who rely on it. Recognizing this challenge, t

For almost a century, parts of California have been gradually sinking, impacting critical infrastructure and the communities who rely on it. Recognizing this challenge, the Department of Water Resources has released a draft Best Management Practices document for public comment that will help local water agencies address this growing concern and support groundwater reliant communities. Click here for the full DWR press release.