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.

Freshwater Systems

California is one of the most hydrologically altered landscapes in the world. As water becomes…>>

Groundwater

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

Surface Flows

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

Terrestrial Systems

In California, a day’s drive can take a visitor from record-setting desert heat to glaciated…>>

Wildlands

Nearly half of California is protected in some land status that prevents most kinds of intensive…>>

Harvested Landscapes

A third of California is privately-owned forestland, woodland or grassland. From redwood forests on…>>

Cultivated Landscapes

California is the leading agricultural state in the country and it’s agriculture generates…>>

Urban Areas and Infrastructure

With California’s population on track to reach 50 million people, the demand for energy,…>>

Fisheries

Wild capture fisheries supply food and jobs for hundreds of millions of people across the globe. Yet…>>

Coastal Conservation

Almost half of the world’s human population lives in coastal areas, and associated coastal…>>

Science in Action

Terrestrial | Planning | Technology

Wildfire and Communities

How can land protection and restoration help protect communities from wildfire?

Terrestrial | Marine | Science

TNC and FEMA

How do we increase climate resilience in ways that work for people and nature?

2002 | Terrestrial | Science | Publications & Reports

Variation in a sparrow’s reproductive success with rainfall: food and predator-mediated processes

Scott A. Morrison, Douglas T. Bolger

Reproductive success of many species in arid environments can be sensitive to rainfall patterns: rainfall events can produce a boom of primary productivity that fuels an ecological response from the…

2002 | Terrestrial | Science | Publications & Reports

Lack of an urban edge effect on reproduction in a fragmentation-sensitive sparrow

Scott A. Morrison, Douglas T. Bolger

Fragmentation-sensitive species – those that tend to disappear when their habitat is fragmented – pose particular challenges for conservation, in part because fragmentation ushers in such…

2000 | Terrestrial | Science | Publications & Reports

Arthropods in urban habitat fragments in southern California: area, age and edge effects

Douglas T. Bolger, Andrew V. Suarez, Kevin R. Crooks, Scott A. Morrison, Ted J. Case

Habitat fragmentation ushers in a wide array of ecological changes, and understanding the drivers and impacts of those changes is critical for conservation management. This study examines an often…