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.


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 | Technology | Economics | Science

Dynamic Conservation

In an era of rapid global change, how can conservationists provide habitat where and when nature needs it most?

Freshwater | Terrestrial | Science

Not Leaving it to Beaver

Can we restore meadows by mimicking beavers?

2018 | Freshwater | Science | Publications & Reports

Groundwater Dependent Ecosystems under the Sustainable Groundwater Management Act: Guidance for Preparing Groundwater Sustainability Plans

Rohde, M.M., S. Matsumoto, J. Howard, S. Liu, L. Riege, E.J. Remson

California's Sustainable Groundwater Management Act (SGMA) of 2014 is landmark legislation that empowers local agencies, known as groundwater sustainability agencies, to sustainably manage groundwater resources for social, economic and environmental benefits. SGMA also includes specific requirements to identify and consider impacts to groundwater dependent ecosystems

2018 | Freshwater | Terrestrial | Science | Publications & Reports

Using ricelands to provide temporary shorebird habitat during migration

Gregory H. Golet, Candace Low, Simon Avery, Katie Andrews, Christopher J. McColl, Rheyna Laney, Mark D. Reynolds

Migratory birds face great challenges due to the climate change, conversion of historical stopover sites, and other factors. To help address these challenges, the launched a dynamic conservation incentive program to create temporary wetland habitats in harvested and fallow rice fields for shorebirds migrating…

2017 | Freshwater | Science | Publications & Reports

Patterns and magnitude of flow alteration in California, USA

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

The importance of the natural flow regime to stream and river health has received growing attention in recent years. Understanding natural flows and patterns of flow alteration is an important first step in improving the management of California’s rivers and streams for human and ecosystem…

2017 | Freshwater | Science | Data

California Natural Flows Database

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

The Nature Conservancy and the United Stated Geological Survey (USGS) partnered to generate estimates of natural flows (expected streamflow in the absence of human modification) in all the streams and rivers in California (1950-2015). For more details on the methods and results see  Patterns and…

2017 | Freshwater | Terrestrial | Planning | Publications & Reports

Identification of potentially suitable habitat for strategic land retirement and restoration in the San Joaquin Desert

H. Scott Butterfield, Rodd Kelsey, Abigail Hart, Tanushree Biswas, Mark Kramer, Dick Cameron, Laura Crane, Erica Brand

California's Sustainable Groundwater Management Act (SGMA) established a framework for sustainable, local groundwater management. SGMA requires groundwater-dependent regions to halt overdraft and bring basins into balanced levels of pumping and recharge. As a result, agricultural land retirement is on the rise in the San Joaquin Valley, California’s largest agricultural region and home to…

2017 | Freshwater | Terrestrial | Planning | Publications & Reports

Rethinking the Grid: Optimizing California’s Transmission System For Renewable Energy

Energy+Environmental Economics for The Nature Conservancy, Arne Olson, Doug Allen, Vivian Li, Emily Leslie

California leads the nation in the transition to a clean energy economy. However, current transmission planning processes limit development of new renewable resources. This report (slide deck), produced for the Conservancy by Energy+Environmental Economics, analyzes an alternative transmission planning framework (Energy-Only) using the San Joaquin Valley as…

2017 | Freshwater | Terrestrial | Marine | Science | Publications & Reports

Conservation Science Catalyst Fund - 2017 Annual Report

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…

2017 | Freshwater | Terrestrial | Marine | Technology | Economics | Science | Publications & Reports

Dynamic conservation for migratory species

Mark D. Reynolds, Brian L. Sullivan, Eric Hallstein, Sandra Matsumoto, Steve Kelling, Matthew Merrifield, Daniel Fink, Alison Johnston, Wesley M. Hochachka, Nicholas E. Bruns, Matthew E. Reiter, Sam Veloz, Catherine Hickey, Nathan Elliott, Leslie Martin, John W. Fitzpatrick, Paul Spraycar, Gregory H. Golet, Christopher McColl, Scott A. Morrison

What if instead of buying habitat, conservationists could rent it when and where nature needs it most? The Conservancy is using predictive models of shorebird movements, data from the citizen science program eBird, and NASA satellite wetland habitat data to create a habitat marketplace of…

2017 | Freshwater | Science | Publications & Reports

Managing diversions in unregulated streams using a modified percent-of-flow approach

Darren W. Mierau, William J. Trush, Gabriel J. Rossi, Jennifer K. Carah, Matthew O. Clifford, Jeanette K. Howard

The California water rights system often dis-incentivizes water management that benefits both nature and people by directing the timing of diversions to the summer when water is the most scarce. It makes more sense to divert water in the winter when it is plentiful, and…

2017 | Freshwater | Terrestrial | Marine | Science | Publications & Reports

Managing consequences of climate-driven species redistribution requires integration of ecology, conservation and social science

Timothy C. Bonebrake, Christopher J. Brown, Johann D. Bell, Julia L. Blanchard, Alienor Chauvenet, Curtis Champion, I-Ching Chen, Timothy D. Clark, Robert K. Colwell, Finn Danielsen, Anthony I. Dell, Jennifer M. Donelson, Birgitta Eveng°ard, Simon Ferrier, Stewart Frusher, Raquel A. Garcia, Roger B. Griffis, Alistair J. Hobday, Marta A. Jarzyna, Emma Lee, Jonathan Lenoir, Hlif Linnetved, Victoria Y. Martin, Phillipa C. McCormack, Jan McDonald, Eve McDonald-Madden, Nicola Mitchell, Tero Mustonen, John M. Pandolfi, Nathalie Pettorelli, Hugh Possingham, Peter Pulsifer, Mark Reynolds , Brett R. Scheffers, Cascade J. B. Sorte, Jan M. Strugnell, Mao-Ning Tuanmu, Samantha Twiname, Adriana Verg´es, Cecilia Villanueva, Erik Wapstra, Thomas Wernberg , Gretta T. Pecl

Climate change is driving the largest global redistribution of the planet’s species since the ice age. Species redistributions present challenges for human well-being, environmental management and sustainable development. Species redistribution also poses new questions for the study of ecosystems, conservation science and human societies that…

2017 | Freshwater | Planning | Science | Publications & Reports

A Global Synthesis of Managing Groundwater Dependent Ecosystems Under Sustainable Groundwater Policy

Melissa M. Rohde, Ray Froend, Jeanette Howard

Groundwater is a vital water supply worldwide for people and nature. However, species and ecosystems that depend on groundwater for some or all of their water needs, known as groundwater dependent ecosystems (GDEs), are increasingly becoming threatened worldwide. This paper provides an overview of how…

2017 | Freshwater | Terrestrial | Economics | Publications & Reports

Market-Based Mechanisms For Securing Environmental Water In California

Sarah Heard, Siobhan King, Eric Hallstein

California’s water supply is becoming increasingly unreliable. During dry times, consumptive use often outstrips supplies. As a result, people and nature suffer. This imbalance of supply and demand will likely grow worse if future demand for agricultural and urban water increases alongside a warming climate.…

2017 | Freshwater | Terrestrial | Planning | Science | Publications & Reports

Population and habitat objectives for avian conservation in California’s Central Valley riparian ecosystems

Kristen E. Dybala, Neil Clipperton, Thomas Gardali, Gregory H. Golet, Rodd Kelsey, Stefan Lorenzato, Ron Melcer, Jr., Nathaniel E. Seavy, Joseph G. Silveira

The Conservancy and partners are working to establish riparian ecosystems that provide sufficient habitat to support genetically robust, self-sustaining, and resilient bird populations in California's Central Valley. In this study, researchers selected 12 riparian landbird focal species as indicators of riparian ecosystem health and are…

2017 | Freshwater | Terrestrial | Planning | Publications & Reports

Informing watershed planning and policy in the Truckee River basin through stakeholder engagement, scenario development, and impact evaluation

Kristen Wilson, Erik Lowe, Stacey Wolny, Barry Nickel , Rodd Kelsey

This study demonstrates how science-based planning with stakeholder input can improve and direct conservation investments across existing state and jurisdictional boundaries. The authors set out to help direct the type, amount, and location of conservaiton investments in the Truckee River watershed in the Sierra Nevada…