Water Quality Degradation

Photo courtesy of the Community Water Center.

SGMA directs groundwater basins to be managed in a manner that avoids ‘significant and unreasonable’ impacts to groundwater quality. To comply, GSAs must understand federal, state and local regulations. A first step is to assemble existing data and information on groundwater quality within a GSA’s basin to determine what further data should be acquired.  When considering actions such as groundwater recharge, GSA’s must appreciate actions that may cause unintended impacts to water quality. A hurdle for Westlands Water District, for example, with  Aquifer Storage and Recovery (ASR) projects, is contamination of imported project water by storage in a geologically challenging and polluted aquifer.

Groundwater quality can be impacted by a host of natural and human-caused sources.  Aquifers can become contaminated by a single point source, such as a decommissioned military base, or by runoff from widespread areas, such as agricultural fields using fertilizers or urban stormwater carrying pollutants from roadways and urban landscapes.   Even within a single aquifer,  groundwater quality can change with the level of the groundwater table itself. Groundwater quality generally degrades with increasing depth within an aquifer, thus declining groundwater levels can lead to poorer water quality and concentration of contaminants.

For more information on groundwater quality, visit the USGS webpage for Groundwater Quality 

Click here to watch the video: Drinking Water Contamination Explained.

Key publications

Guide to Water Quality Requirements Under SGMAGuide to Protecting Drinking Water Quality Under SGMAProtecting Groundwater Quality in CA

A Guide to Water Quality Requirements Under the Sustainable Groundwater Management Act

Unlike most other undesirable results, water quality degradation is the subject of robust federal, state and local regulatory regimes carried out by a number of different entities. While the State and Regional Water Resources Control Boards have the broadest responsibilities to protect groundwater quality, many other agencies also have relevant responsibilities.

This Guide is intended to assist GSAs along with other agencies and stakeholders in understanding the meaning of water quality degradation, and to provide insights into how GSAs can successfully fulfill their legal responsibilities regarding groundwater quality.

Click here to download this publication.

Guide to Protecting Drinking Water Quality Under SGMA

GSPs must identify groundwater quality issues including known groundwater contamination locations and must also collect data from each aquifer to determine groundwater quality trends. Data gaps must be identified and addressed. When developing minimum thresholds and measurable objectives for degraded water quality, GSAs must consider existing drinking water standards and identify drinking water supply wells in order to monitor for degradation of drinking water sources.

This publication is intended to be a resource for community water decision-makers who are engaged in the implementation of the Sustainable Groundwater Management Act (SGMA) and are interested in learning about best management practices for addressing drinking water concerns.

Click here to download this publication.

Protecting Groundwater Quality in California

Protecting groundwater quality is an essential component of sustainable water management. However, active groundwater management often focuses on maintaining groundwater quantity – a target that does not always ensure groundwater quality goals are met. In fact, there are many ways in which both supply- and demand-side management actions can inadvertently impact groundwater quality. These impacts range from improving groundwater quality to unintentionally creating new groundwater quality problems.

The purpose of this document is to provide guidance to groundwater managers, consultants, and stakeholders on groundwater quality considerations associated with management actions and methods for preventing unintended groundwater contamination.

Click here to download this publication.

State Water Board FAQ: Water Quality

Questions answered include: Why consider water quality? How do the authorities granted to GSAs in SGMA relate to water quality?  Can a GSA set objectives in a GSP that improve water quality in the basin or address water quality issues beyond the minimum requirements of SGMA? Why should GSAs consider the needs of drinking water systems? Where can a GSA find information on water quality data and existing programs in a specific basin?

Click here to view/download FAQs in English.
Haga clic aquí para ver / descargar la hoja de preguntas frecuentes en español.

State Water Board programs to protect groundwater quality

The State Water Board and the nine regional water boards protect groundwater through numerous regulatory and planning programs.  The key elements of the water board’s approach include identifying and updating beneficial uses and water quality objectives, regulating activities that can impact the beneficial uses of groundwater, and preventing future groundwater impacts through planning, management, education, monitoring, and funding.

Click here for more information on the State Water Board's role in regulating groundwater quality.

The State Water Board and the regional water boards have numerous programs to address this.  Some of them are:

The Irrigated Lands Program regulates discharges from irrigated agricultural lands.  These discharges include irrigation runoff, flows from tile drains, and stormwater runoff. These discharges can affect water quality by transporting pollutants, including pesticides, sediment, nutrients, salts, pathogens, and heavy metals, from cultivated fields into surface waters, or by infiltrating down into the underlying groundwater aquifer.  Click here to learn more about the Irrigated Lands Program.

The Drinking Water Source Assessment and Protection (DWSAP) Program addresses both groundwater and surface water sources. The groundwater portion of the Program serves as the state’s wellhead protection program as required by the federal Safe Drinking Water Act.   The program has two primary elements:  Drinking Water Source Assessment and Source Protection. Since 1997, the  Program has with the assistance of others—34 counties, the California Rural Water Association, and more than 500 water systems—completed assessments for nearly all the public drinking water sources in the state.    Click here to learn more about the Drinking Water Source Assessment and Protection Program

The Land Disposal Program regulates the discharge to land of certain solid and liquid wastes. In general, these wastes cannot be discharged directly to the ground surface without impacting groundwater or surface water, and therefore must be contained to isolate them from the environment.  Click here to learn more about the Land Disposal Program.

The Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS) is a collaborative basin planning effort aimed at developing and implementing a comprehensive salinity and nitrate management program.  The Salt and Nitrate Control Program provides a new framework for the Regional Water Board to regulate salt and nitrate, while also ensuring a safe drinking water supply.  While the CV-SALTS program is not directly related to SGMA, there is potential for significant overlap with GSAs implementing their GSPs.  Click here to learn more about CV-SALTS program.

Learn more about how the Water Boards protect groundwater by clicking here.

Groundwater Ambient Monitoring and Assessment (GAMA) Program

The Groundwater Ambient Monitoring and Assessment (GAMA) Program is California’s comprehensive groundwater quality monitoring program that was created by the State Water Resources Control Board in 2000.  The GAMA Program is based on interagency collaboration with the State and Regional Water Boards, Department of Water Resources, Department of Pesticide Regulations, U.S. Geological Survey, and Lawrence Livermore National Laboratory, and cooperation with local water agencies and well owners.

Groundwater Ambient Monitoring and Assessment (GAMA) Program

The main goals of GAMA are to improve statewide comprehensive groundwater monitoring and increase the availability to the general public of groundwater quality and contamination information.

California is very reliant on groundwater supplies. Having access to safe, clean water is critical to sustain society, the environment, business, industry, and agriculture. Comprehensively monitoring groundwater quality under the GAMA Program is an important part of managing our water resources.

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Assessing groundwater contamination risks in California’s disadvantaged communities

Many communities in California rely on groundwater supplies that are contaminated with pollutants such as metals, nitrates, and hydrocarbons. For low-income and disadvantaged communities with limited access to water treatment technologies, this is an especially challenging problem that puts residents at risk.  To help identify communities at risk of groundwater contamination, the Office of Water Programs at Sacramento State University used openly available data for groundwater monitoring and social and economic indicators to map groundwater contamination risk across the state.

Click here to learn more about groundwater contamination risks in California's disadvantaged communities.

The interactive maps featured below are designed to help managers and policymakers identify disadvantaged communities (DACs) and severely disadvantaged communities (SDACs) that physically reside over contaminated groundwater basins and may use these basins for drinking water supplies. As specified in section 79505.5 of the California Water Code, such communities are defined as:

      • DACs are communities with a median household income (MHI) less than 80% of the statewide average* (MHI<$51,026).
      • SDACs are communities with an MHI less than 60% of the statewide average* (MHI<$38,270).

The interactive maps can help direct investments to clean-up contaminated groundwater wells using current and future funding.

Click here to view interactive maps at the Office of Water Programs at Sacramento State University.

Department of Pesticide Regulation’s Groundwater Protection Program

DPR’s Groundwater Protection Program evaluates and samples for pesticides to determine if they may contaminate groundwater, identifies areas sensitive to pesticide contamination and develops mitigation measures to prevent that movement.  The Department also adopts regulations and does outreach to carry out those mitigation measures. The measures are designed to prevent continued movement to groundwater in contaminated areas and to prevent problems before they occur in other areas.

Click here to learn more about the Department of Pesticide Regulation's Groundwater Protection Program.

Blending environmental monitoring, scientific research and computer mod­eling, the Department of Pesticide Regulation (DPR) Ground Water Protec­tion Program addresses current and potential contamination.  DPR continually monitors for agricultural pesticides that have been restrict­ed because they were detected in ground water. Annual sampling conducted in a domestic well monitoring network in vulnerable areas helps DPR track levels of pesticides being regulated to protect ground water.

Learn more about the Department of Pesticide Regulation’s Groundwater Protection Program by clicking here.

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Articles on water quality at Maven’s Notebook

  • Notebook water quality posts

Explore water quality at the California Water Library


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