In a normal year, groundwater accounts for 40 percent of California’s water supply. That number jumps to 60 percent during a drought. It’s also critically important for sustaining certain types of aquatic, terrestrial and coastal ecosystems.

Yet decades of unregulated groundwater withdrawal has compromised that ability to provide for people and nature. Wells dry up, water quality declines, and rivers, wetlands, and springs disappear.

To address this problem, California passed legislation requiring that groundwater basins be managed sustainably. We still face gaps, however, in our understanding of how to manage these basins to ensure the health of the ecosystems they support. Conservancy scientists are working with water managers and state agencies to close those gaps.

Science in Action

Freshwater | Science

Groundwater Dependent Ecosystems

How can we manage groundwater to benefit both people and nature?

Freshwater | Technology | Science

Groundwater for Ecosystem Health

How much groundwater do ecosystems need to survive?

2021 | Freshwater | Terrestrial | Science | Publications & Reports

Cannabis farms in California rely on wells outside of regulated groundwater basins

Christopher Dillis, Van Butsic, Jennifer Carah, Samuel Zipper, Theodore Grantham

Water management practices for cannabis farming in California are not well understood. This study examined permit reporting data and found that the vast majority (>75%) of permitted cannabis farms use groundwater wells to source water, with many wells located outside regulated groundwater basins. Groundwater pumping…


2021 | Freshwater | Planning | Science | Publications & Reports

Mind the Gaps: The Case for Truly Comprehensive Sustainable Groundwater Management

Barton H. Thompson, Jr., Melissa M. Rohde, Jeanette K. Howard, Sandi Matsumoto

In 2014, California’s landmark Sustainable Groundwater Management Act (SGMA) promised comprehensive management of California’s groundwater. This report, Mind the Gaps: The Case for Truly Comprehensive Sustainable Groundwater Management, based on joint analysis by Water in the West at Stanford University and The Nature Conservancy, finds…


2021 | Freshwater | Terrestrial | Planning | Technology | Science | Data

Natural Communities Commonly Associated with Groundwater Version 2.0 (NCCAG 2.0)

Kirk Klausmeyer, Jeanette Howard, Melissa Rohde, Charlotte Stanley

The first step to sustainably manage groundwater dependent ecosystems (GDEs) is to identify where they are. The Nature Conservancy developed a statewide spatial database that provides locations of seeps and springs, wetlands, and vegetation likely to depend on groundwater. This database (version 2.0) is an…


2021 | Freshwater | Planning | Maps & Webmaps

ICONS: Interconnected Surface Water in the Central Valley

Charlotte Stanley, Kirk Klausmeyer

This dataset categorizes the rivers and streams in the Central Valley on the likelihood that they are interconnected surface water (ISW) -- surface water hydraulically connected to groundwater. The dataset includes information on the average, maximum, and minimum depth to groundwater, using groundwater elevation…


2021 | Freshwater | Planning | Science | Publications & Reports

Managing Groundwater to Ensure Ecosystem Function

Laurel Saito, Bill Christian, Jennifer Diffley, Holly Richter, Melissa M. Rohde, Scott A. Morrison

In this paper, we describe minimum provisions for planning, managing, and monitoring groundwater in a manner that collectively can lower the risk of harm to groundwater-dependent ecosystems and species, as well as providing sustainable groundwater resources for communities. The paper has a special emphasis on…


2021 | Freshwater | Terrestrial | Planning | Science | Publications & Reports

Rewilding Agricultural Landscapes: A California Study in Rebalancing the Needs of People and Nature

H. Scott Butterfield, T. Rodd Kelsey, and Abigail K. Hart, Editors

As the world population grows, so does the demand for food, putting unprecedented pressure on agricultural lands. At the same time, climate change, soil degradation, and water scarcity mean that productivity of many of these lands is deteriorating. In many desert dryland regions, drinking wells…


2020 | Freshwater | Planning | Technology | Economics | Science | Publications & Reports

Base of fresh water, groundwater salinity and well distribution across California

Mary Kang, Debra Perrone, Ziming Wang, Scott Jasechko, Melissa M. Rohde

To ensure that California’s groundwater is sustainably managed in the future and over the long-term, current state definitions of what constitutes groundwater may need to be revised, according to this research published in PNAS. A research collaboration between McGill University, University of California Santa…


2020 | Freshwater | Terrestrial | Technology | Science | Publications & Reports

Conservation of Mojave Desert springs and associated biota: status, threats, and policy opportunities

Sophie S. Parker, Andy Zdon, William T. Christian, Brian S. Cohen, Maura Palacios Mejia, Naomi S. Fraga, Emily E. Curd, Kiumars Edalati, Mark A. Renshaw

This paper presents results from the Mojave Desert Springs research project, and discusses why the conservation of these groundwater-dependent ecosystems is so critical to biodiversity. The authors present results of a comprehensive survey of Mojave Desert springs including hydrological and ecological observations, and an…


2020 | Freshwater | Terrestrial | Science | Publications & Reports

A meta-analysis contrasting active versus passive restoration practices in dryland agricultural ecosystems

M. Florencia Miguel, H. Scott Butterfield, Christopher J. Lortie

This meta-analysis provides a global synthesis of the which restoration practices – active vs. passive – are most successful at restoring plants, animals, and other ecosystem functions to dryland agricultural (grazing and farmlands) ecosystems, including the San Joaquin Valley of California where The Nature Conservancy…


2020 | Freshwater | Terrestrial | Technology | Science | Publications & Reports

The utility of environmental DNA from sediment and water samples for recovery of observed plant and animal species from four Mojave Desert springs

Maura Palacios Mejia, Emily Curd, Kiumars Edalati, Mark A. Renshaw, Roy Dunn, Daniel Potter, Naomi Fraga, Jenna Moore, Justin Saiz, Robert Wayne, Sophie S. Parker

This paper presents results from the Mojave Desert Springs research project. The authors used an environmental DNA (eDNA) technique to assess biodiversity at four naturally occurring springs. They compared the effectiveness of detecting DNA in water and sediment with conventional field survey and…


2020 | Freshwater | Science | Publications & Reports

Groundwater Thresholds for Ecosystems: A Guide for Practitioners

Melissa M. Rohde, Laurel Saito, Ryan Smith

In addition to benefiting humans, groundwater is a critical water supply to many ecosystems, providing a buffer during dry periods and critical habitat for rare and endemic species. Increasing groundwater use to meet human water demands can outcompete these ecosystem water needs, causing irreversible damage to…


2020 | Freshwater | Terrestrial | Planning | Science | Publications & Reports

Shaping land use change and ecosystem restoration in a water-stressed agricultural landscape to achieve multiple benefits

Benjamin P. Bryant, T R. Kelsey, Adrian L. Vogl, Stacey A. Wolny, Duncan J. MacEwan, Paul C. Selmants, Tanushree Biswas, H S. Butterfield

Irrigated agriculture has grown rapidly over the last 50 years, helping food production keep pace with population growth, but also leading to significant habitat and biodiversity loss globally. Now, in some regions, land degradation and overtaxed water resources mean historical production levels may need to…


2020 | Freshwater | Terrestrial | Technology | Science | Publications & Reports

Mojave Desert Springs: setting an ecological baseline

Sophie S. Parker

This article appears in the Desert Report, a news publication of the Sierra Club California/Nevada Desert Committee. The article introduces the Mojave Springs Research Project, led by The Nature Conservancy, that involves a research collaboration with UCLA, the California Botanic Garden, and Partner Engineering and…


2019 | Freshwater | Planning | Science | Publications & Reports

Dynamic multibenefit solutions for global water challenges

Melissa M. Rohde, Mark Reynolds, Jeanette Howard

In this article, the authors provide an example of how dynamic multi-benefit solutions used to provide “pop-up” wetland habitat for migratory birds also replenishing depleted aquifers to create environmental and water supply benefits and broadens it to the global scale. Additionally, this article outlines six…


2019 | Freshwater | Science | Publications & Reports

Cannabis and residential groundwater pumping impacts on streamflow and ecosystems in Northern California

Samuel C. Zipper, Jennifer K. Carah, Christopher Dillis, Tom Gleeson, Ben Kerr, Melissa M. Rohde, Jeanette K. Howard, Julie K.H. Zimmerman

Using a newly developed tool for estimating streamflow depletion from groundwater pumping, this study examined the impacts of ongoing groundwater pumping on streamflow and aquatic ecosystems in the Navarro watershed in rural, coastal California. The study found that common uses of groundwater in the watershed,…


2019 | Freshwater | Science | Publications & Reports

A Transdisciplinary Approach to Characterize Hydrological Controls on Groundwater-Dependent Ecosystem Health

Melissa M. Rohde, Sara B. Sweet, Craig Ulrich, Jeanette Howard

Groundwater plays an essential role in supporting freshwater species, riparian habitats, and migratory birds. These ecological communities, commonly referred to as groundwater-dependent ecosystems (GDEs), can suffer undesirable impacts from unsustainable pumping practices. This study assessed whether ecosystem health varied with groundwater availability in riparian forests in California’s…


2019 | Freshwater | Terrestrial | Science | Publications & Reports

First known survey of cannabis production practices in California

Houston Wilson, Hekia Bodwitch, Jennifer Carah, Kent Daane, Christy Getz, Theodore E. Grantham, Van Butsic

Cannabis has been an industry in the shadows for many decades and little studied. In partnership with U.C. Berkeley and U.C. Cooperative Extension, the Conservancy staff developed the first cannabis growers survey on cultivation practices in California. The goal of the survey was to understand…


2019 | Freshwater | Economics | Publications & Reports

Economic Tools to Achieve Groundwater Sustainability for Nature: Two Experimental Case Studies from California

Sandi Matsumoto, Melissa M. Rohde, Sarah Heard

Groundwater is a critical water supply around the world and is increasingly under threat from pumping that exceeds natural replenishment. Successful implementation of California's Sustainable Groundwater Management Act (SGMA) depends local agencies working with stakeholders to develop plans and implement projects that reduce groundwater use,…


2019 | Freshwater | Science | Publications & Reports

Critical Species LookBook: A compendium of California's threatened and endangered species for sustainable groundwater management

Rohde MM, Seapy B, Rogers R, Castañeda X, editors

Plant and animal species can rely on groundwater directly or indirectly for water, nutrients, and stable temperatures. The Critical Species LookBook is a compendium of 84 state and federally listed species likely to rely on groundwater in California. This document provides groundwater-relevant information for each…


2019 | Freshwater | Science | Publications & Reports

Rapid and Accurate Estimates of Streamflow Depletion Caused by Groundwater Pumping Using Analytical Depletion Functions

Samuel C. Zipper, Tom Gleeson, Ben Kerr, Jeanette K. Howard, Melissa M. Rohde, Jennifer Carah, Julie Zimmerman

Reductions in streamflow from groundwater pumping can negatively impact water users and aquatic ecosystems but are challenging to estimate due to the time and expertise required to develop numerical models often used in water management. This paper develops a new approach – a combination of…