California is one of the most hydrologically altered landscapes in the world. As water becomes ever more scarce and the human population continues to grow, that vast engineered system strains to meet the needs of people let alone the needs of nature. 

Water rights allocations far exceed actual surface water supply, and millions of wells tap groundwater to meet the increasing demands of farms and communities. As groundwater reservoirs are depleted they can in turn reduce surface flows – exacerbating a vicious cycle in which people and nature both lose. Rivers, wetlands and groundwater-dependent ecosystems are caught in this struggle for an increasingly limited resource. Nearly half of California’s roughly 4,000 freshwater species are considered vulnerable to extinction. Of the taxa that are found nowhere but California – our endemic freshwater biodiversity – 90 percent are at risk.

But there is hope. While it is impossible to return natural flows to most of California’s rivers and streams, we can – through science, technology, and innovative market tools – endeavor to deliver water when and where nature needs it most.

Groundwater

In a normal year, groundwater accounts for 40 percent of California’s water supply. That number jumps to 60… >>

Surface Flows

Californians have fundamentally altered many of the state’s rivers and streams with dams, pipes, and diversions, and the… >>

Science in Action

Freshwater | Terrestrial | Science

Rewilding the San Joaquin Valley

40 years of science sets the course for the largest recovery of species in U.S. history

Freshwater | Terrestrial | Marine | Science

Research for Impact

How do we design scientific research to have impact in the world?

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 | Science | Publications & Reports

Shifting geographies of legal cannabis production in California

Christopher Dillis, Eric Biber, Hekia Bodwitch, Van Butsic, Jennifer Carah, Phoebe Parker-Shames, Michael Polson, and Theodore Grantham

This study used permitting and GIS data to explore geographic characteristics of legal cannabis farms in California. The study found two divergent paths of development - one characterized by numerous, smaller farms in rugged, tree-covered landscapes in historical cannabis producing regions (Humboldt, Mendocino, Trinity counties),…


2021 | Freshwater | Science | Maps & Webmaps

California Natural Flows Webapp

Julie K.H. Zimmerman, Daren M. Carlisle, Jason T. May, Kirk R. Klausmeyer, Theodore E. Grantham, Larry R. Brown, Jeanette K. Howard, Nathaniel Rindlaub, Falk Schuetzenmeister

Water is essential for California’s people, economy, and environment. Centuries of water management through dams and diversion have altered the flows in many streams and rivers, which can harm the freshwater ecosystems. The Nature Conservancy and the United States Geological Survey (USGS), and other partners…


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 | Terrestrial | Marine | Planning | Technology | Science | Publications & Reports

Nature-Based Climate Solutions: A Roadmap to Accelerate Action in California

Sydney J. Chamberlin, Michelle Passero, Ashley Conrad-Saydah, Tanushree Biswas, Charlotte K. Stanley

California’s natural and working lands – its forests, grasslands, wetlands, farmlands, rangeland, and urban green spaces – provide Californians with numerous environmental, social, and economic benefits, including greenhouse gas reductions (e.g., carbon sequestration). However, extreme heat events, droughts, floods, wildfires, development, and other anthropogenic impacts…


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 | Marine | Science | Publications & Reports

Conservation Science Catalyst Fund - 2020 Annual Report

Brynn Pewtherer

The Nature Conservancy deploys science to help overcome major challenges facing people and nature. In today’s fast-paced world, turning threats to nature into opportunities for conservation requires agility. The Conservation Science Catalyst Fund enables our science team to mobilize quickly — and produce the information…


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 | Terrestrial | Marine | Science | Publications & Reports

Bridging the knowledge‐implementation gap between agency and academia: A case study of a graduate research experience

Aviv Karasov‐Olson, Alicia K. Bird, Amy C. Collins, Emily E. Graves, Julea A. Shaw, Eric F. Tymstra, T. Rodd Kelsey, Mark W. Schwartz

Conservation biology is particularly susceptible to the knowledge‐implementation gap where academic pursuits do not always meet the needs of practitioners. Providing future practitioners with relevant training and experiences as graduate students can help narrow this gap. An example of one such experience was a partnership…


2020 | Freshwater | Terrestrial | Technology | Science | Maps & Webmaps

Planting Stormwater Solutions

Brian Cohen, Kelsey Jessup, Sophie Parker, John Randall, Jill Sourial

Cities across Southern California are investing in new infrastructure to address the challenges of stormwater management. We promote the use of nature-based solutions to ensure projects both treat stormwater and yield multiple additional benefits. TNC’s spatial analyses, summarized in this poster, help prioritize where to site…


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…