Restoring California’s Largest River

How can we restore large rivers and floodplains to benefit nature and people?

Aerial view of the Sacramento River. In the foreground is 15-year-old restored riparian habitat that is now part of the USFWS Sacramento River National Wildlife Refuge.  Photo: © Rich Reiner | TNC

The Sacramento River is the most important river in California for both people and nature. It stretches 384 miles, and drains the inland slopes of the Klamath Mountains, the Cascade Range, the Coast Ranges and the northern Sierra Nevada. The river supplies 35% of the state’s developed water supply, and contains critical habitats for a multitude of commercially and ecologically important species.

School children from Gerber helping with riparian restoration planting along the Sacramento River.  Photo: © TNC

Although still vitally important, today’s Sacramento River is highly degraded relative to its former condition. Fish and bird populations have plummeted as 90% of the river’s forests have been cleared and water has been diverted for agriculture and municipal uses. The once meandering river is no longer free to carve its own path across the valley floor, creating the habitats that native species evolved to depend upon. In many places, the river is locked in place by riprap (rocks or other materials that armor shorelines), and levees, which disconnect it from its historic floodplain.

The Nature Conservancy is working to restore the river’s ecosystem and enhance the natural services that the river provides to people, including flood protection, water quality, and recreation.

Applying our Science

Nature Conservancy scientists have advanced restoration of the Sacramento River by demonstrating both the ecological benefits and the societal gains that result from healthy riverine ecosystems. These scientific advances have helped us overcome initial opposition to river restoration. Specifically, our studies:

  • illustrated how habitat restoration can help recover special-status wildlife species (e.g., neotropical migratory birds, bats, and beetles), which can lead to a reduction in regulatory constraints placed on local farmers;
  • revealed how converting farmland to habitat can provide income from enhanced recreation experiences within expanded wildlife refuges;
  • dispelled the concern that agricultural pest species increase when orchards are replaced with riparian habitat;
  • demonstrated that flood events can be beneficial to floodplain farms by reducing the abundance of small mammals pests species;
  • showed that restored riparian floodplains can provide better flood protection than the orchards they replaced;
  • assessed progress made toward past restoration goals, focusing on efficiency of conservation strategies, successes and failures, to set priorities and inform future efforts; and
  • developed and applied a novel “Ecological Flows Tool” to evaluate the impacts of different patterns of river flow on ecosystems.

Sacramento River riparian restoration sites of varying ages. A) Newly planted restoration site, B) Six-year old restoration site, and C) Fifteen-year old site. Photo: © Greg Golet

By sharing the results of our studies with local stakeholders, river managers, and the scientific community, the Conservancy gained the support needed to restore over 6,000 acres of floodplain habitat in what has become one of the largest and most successful river restoration projects in the United States.


Related Products

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

Sacramento River: balancing ecological and social restoration goals to restore riparian habitat along a lowland floodplain river, California, USA

Case study by: K.D. Holl, G.H. Golet

Advancing conservation requires understanding the constraints imposed on natural systems by human societies. This understanding typically comes from engagement with local stakeholders, as opposed to from scholastic training. A recent textbook on restoration ecology by Karen Holl seeks to alleviate this problem by providing real-world…

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…

2016 | Terrestrial | Science | Publications & Reports

Evidence for genetic pollution of a California native tree, Platanus racemosa, via recent, ongoing introgressive hybridization with an introduced ornamental species

Matthew G. Johnson, Kylene Lang, Paul Manos, Greg H. Golet, Kristina A. Schierenbeck

When non-native ornamental species spread into wild landscapes they can displace natives that have greater wildlife habitat value. Controlling the spread of a non-native species can be difficult when it hybridizes with a native species, because it may no longer be visually distinguishable. This study…

2016 | Terrestrial | Science | Publications & Reports

Response of medium- and large-sized terrestrial fauna to corridor restoration along the middle Sacramento River

Vasilissa V. Derugin, Joseph G. Silveira, Gregory H. Golet, Gretchen LeBuhn

In restoration ecology, understanding how and when species colonize newly created habitat is critically important for assessing progress toward restoration goals. By using camera traps to take a closer look, authors of this study found that riparian corridor restoration can support medium-and large-sized mammalian predators…

2013 | Freshwater | Terrestrial | Planning | Science | Publications & Reports

Successes, Failures and Suggested Future Directions for Ecosystem Restoration of the Middle Sacramento River, CA

Golet G.H., D.L. Brown, M. Carlson, T. Gardali, A. Henderson, K.D. Holl, C.A. Howell, M. Holyoak, J. Hunt, G.M. Kondolf, E.W. Larsen, R.A. Luster, C. McClain, C. Nelson, S. Paine, W. Rainey, Z. Rubin, F. Shilling, J.G. Silveira, H. Swagerty, N.M. Williams, D.M. Wood

Large-scale ecosystem restoration projects seldom undergo comprehensive evaluation to determine project effectiveness. Consequently, there are missed opportunities for learning and strategy refinement. In their synthesis of 36 ecological indicators of Sacramento River riparian restoration, the authors found steady progress in the restoration of riparian habitats and…

2013 | Freshwater | Terrestrial | Science | Publications & Reports

Decline and Recovery of Small Mammals after Flooding: Implications for Pest Management and Floodplain Community Dynamics

Golet G.H., J. Hunt, D. Koenig

Floodplains often are managed both for agriculture and as habitat for native species. On the Sacramento River, farmers have expressed concern that natural areas may be sources of pests to adjoining farmlands, generating opposition to riparian restoration. This study examined this question by studying small…

2011 | Terrestrial | Science | Publications & Reports

Temporal and taxonomic variability in response of fauna to riparian restoration

G.H. Golet, T. Gardali, J.W. Hunt, D.A. Koenig, N.M. Williams

Most assessments of ecological restoration success track a single type of species over a single season. This study explores the limitations of such studies by examining how birds, rodents, bees and beetles responded to restoration along the Sacramento River for up to five years. The authors…

2008 | Freshwater | Terrestrial | Science | Publications & Reports

Wildlife Response to Restoration on the Sacramento River

Golet G.H., T. Gardali, C. Howell, J. Hunt, R. Luster, B. Rainey, M. Roberts, H. Swagerty, N. Williams

Studies that assess the success of riparian restoration projects seldom focus on wildlife. More often, vegetation is studied, with the assumption that animal populations will recover once adequate habitats are established. Authors of this paper present an exception: findings of a suite of studies that…

2006 | Freshwater | Terrestrial | Science | Publications & Reports

Abundance Patterns of Landbirds in Restored and Remnant Riparian Forests on the Sacramento River, California, U.S.A.

Gardali T. , A.L. Holmes, S.L. Small, N. Nur, G.R. Geupel, G.H. Golet

Restoration efforts on the Sacramento River are focusing on revegetating the land with native plants and restoring natural river processes in an attempt to recover wildlife populations. To evaluate the success of these efforts, surveys were conducted of landbirds on revegetated and remnant riparian plots.…

2006 | Freshwater | Terrestrial | Planning | Economics | Science | Publications & Reports

Assessing societal impacts when planning restoration on large alluvial rivers: A case study of the Sacramento River Project, CA

Golet G.H., M.D. Roberts , E.W. Larsen, R.A. Luster, R. Unger, G. Werner, G.G. White.

River restoration projects have the potential to influence many of the services that rivers provide to people, yet rarely is this studied in a comprehensive manner. This paper reports on a set of coordinated studies that were conducted to evaluate the effects of alternative restoration…