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?

2018 | Freshwater | Science | Microsite

Groundwater Resource Hub

Sandi Matsumoto, Gregg Werner, Melissa Rohde, Kirk Klausmeyer

Groundwater dependent ecosystems (GDEs) are plant and animal communities that require groundwater to meet some or all of their water needs. GDEs provide important benefits to California including habitat for animals, water supply, water purification, flood mitigation, erosion control, recreational opportunities and enjoyment of California’s…


2018 | Freshwater | Science | Publications & Reports

Mojave Desert Springs and Waterholes: Results of the 2015-16 Mojave Desert Spring Survey

Prepared by Andrew Zdon & Associates Inc. for Transition Habitat Conservancy, The Bureau of Land Management, and The Nature Conservancy

The Mojave Desert within California, which spans four counties, exists as one of the most important ecological regions in the southwestern United States. Both the groundwater and surface water in the region support isolated, unique and diverse ecosystems, while also supporting human needs through domestic,…


2018 | Freshwater | Terrestrial | Planning | Science | Publications & Reports

Ecological Values of the Amargosa River in California

Sophie S. Parker, Jim Moore, Leonard Warren

The 185 mile-long Amargosa River, one of only two rivers with perennial flow in the California portion of the Mojave Desert, is fed by an ancient groundwater aquifer. The river provides habitat for hundreds of organisms, including a unique suite of rare, endemic, and imperiled…


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


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 | 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.…


2016 | Freshwater | Science | Publications & Reports

Benefits and Economic Costs of Managed Aquifer Recharge in California

Debra Perrone, Melissa M. Rohde

Managed aquifer recharge (MAR) projects can play an important role in ensuring California manages its groundwater sustainably. This study, the first to investigate the benefits and economic costs of MAR projects in the state, found California MAR projects to be a cost-effective storage strategy, exhibit a…


2016 | Freshwater | Maps & Webmaps

How and Where Nature Uses Groundwater

Kirk Klausmeyer, Jeanette Howard, Sandi Matsumoto, Sally Liu, Melissa Rohde

Groundwater is essential to the health and viability of plants, animals and ecosystems. Many tree species, like willows and cottonwoods, rely on groundwater to survive seasonal and annual dry spells. Fish and other aquatic life need groundwater to keep rivers flowing. When unsustainable management causes groundwater levels…


2016 | Freshwater | Science | Publications & Reports

Sustainable Groundwater Management: What We Can Learn from California's Central Valley Streams

The Nature Conservancy, RMC Consultants, Inc.

Groundwater is intimately connected to surface water, which has profound implications for sustainable water resource management. California has historically overlooked this important interaction and as a consequence, decisions about groundwater extractions have generally failed to address the resulting impacts to aquatic ecosystems such as rivers,…


2016 | Freshwater | Science | Publications & Reports

Groundwater and Stream Interaction in California’s Central Valley: Insights for Sustainable Groundwater Management

The Nature Conservancy, RMC Consultants, Inc.

Groundwater is intimately connected to surface water, which has profound implications for sustainable water resource management. California has historically overlooked this important interaction and as a consequence, decisions about groundwater extractions have generally failed to address the resulting impacts to aquatic ecosystems such as rivers,…


2015 | Freshwater | Planning | Data

California Freshwater Species Database v2

Jeanette Howard, Kirk Klausmeyer, Kurt Fesenmyer

The California Freshwater Species Database is the first comprehensive geospatial database of California’s freshwater species compiled and standardized into single format from nearly 500 sources. It provides a single source for geodata covering the plants and animals that rely on California’s freshwater resources to survive.…


2015 | Freshwater | Planning | Science | Publications & Reports

Patterns of Freshwater Species Richness, Endemism, and Vulnerability in California

Jeanette K. Howard, Kirk R. Klausmeyer, Kurt A. Fesenmyer, Joseph Furnish, Thomas Gardali, Ted Grantham, Jacob V. E. Katz, Sarah Kupferberg, Patrick McIntyre, Peter B. Moyle, Peter R. Ode, Ryan Peek, Rebecca M. Quiñones, Andrew C. Rehn, Nick Santos, Steve Schoenig, Larry Serpa, Jackson D. Shedd, Joe Slusark, Joshua H. Viers, Amber Wright, Scott A. Morrison

The California Freshwater Species Database is the first comprehensive geospatial database of California’s freshwater species compiled and standardized into single format from nearly 500 sources. It provides a single source for geodata covering the plants and animals that rely on California’s freshwater resources to…


2015 | Freshwater | Data

Groundwater Dependent Ecosystems in California data

Jeanette Howard, Matt Merrifield

The California Freshwater Species Database is the first comprehensive geospatial database of California’s freshwater species compiled and standardized into single format from nearly 500 sources. It provides a single source for geodata covering the plants and animals that rely on California’s freshwater resources to survive.


2013 | Freshwater | Planning | Science | Publications & Reports

Below the Surface: California’s Freshwater Diversity

Jeanette Howard, Kirk Klausmeyer, Kurt Fesenmyer

Californians face profound decisions regarding the management of their state’s increasingly limited water supply. Critical for decision-making is information about the plants and animals that also rely on California’s freshwater resources to survive. This report includes an atlas of the freshwater biodiversity patterns in California,…


2010 | Freshwater | Publications & Reports

Mapping Groundwater Dependent Ecosystems in California

Jeanette Howard, Matt Merrifield

In 2014 the California legislature passed a three-bill package (SB 1168, AB 1739, and SB 1319) of groundwater reform legislation that was the most significant update of California water policy in several decades. The legislation provides authorities and guidance for local agencies to develop sustainable…