The Delta: A Water Source for Most Californians

Whether they know it or not, almost all Californians rely upon the Sacramento–San Joaquin Delta. In fact, it supplies one of our most vital and precious natural resources: freshwater.

The 700,000-acre Delta is the heart of the largest estuary on the West Coast of the Americas and home to 750 distinct species of plants and animals, some found nowhere else on Earth. It also sustains farmland that produces about 45 percent of the nation’s fruits and vegetables.

Each year streamflow originating in the Sierra Nevada and the coastal and southern Cascade ranges is transported throughout central and southern California, comprising one of the world’s largest water-delivery systems. This maze of tributaries, sloughs and islands, located east of the San Francisco Bay Area, stretches nearly 50 miles from Sacramento south to Tracy.

On the Verge of Collapse

The Delta is an ecosystem on the verge of collapse due to invasive species, pollution and the destruction of most of the area’s wetland and river habitat. Existing water-supply operations have also had profound impacts on the Delta. They have transformed the estuary into what is now essentially a freshwater lake and have reversed the natural direction of the rivers flowing out of the Delta. As a result of these and other issues, several native species are on the brink of extinction. Unless there is a sustainable path forward in the Delta, we will continue to see ecological collapse of the estuary with further reductions in water supply for cities and agriculture.

Many of the Delta’s earthen levees are just one earthquake or major flood away from collapse. In addition to the environmental impacts of a natural disaster, such an event would disrupt the water supply for millions of Californians for months or years and could have a catastrophic impact on our economy.

Climate change is bringing additional pressures to the Delta. Sea-level rise is pushing more saltwater into the Delta and adding pressure to its fragile levees. Less snow and more rain in the Sierra Nevada will increase the winter river flow and further strain the levees as flooding becomes more intense.

Working Against the Clock

The Nature Conservancy has protected and restored nearly 25,000 acres of wildlife habitat in the Delta and manages a wildlife-friendly farm operation on Staten Island, next to the Cosumnes and Mokelumne rivers, which is critical wintering habitat for sandhill cranes, shorebirds and other migratory birds.

The Conservancy has also been deeply engaged in Delta planning efforts and studies, including the Bay Delta Conservation Planning (BDCP) process. In 2009 Conservancy scientists completed an independent study of the Delta using our Conservation by Design process. Our findings led us to conclude that the only way to save this beautiful and unique region is to restore significant portions of habitat as well as the natural water-flow conditions under which native Delta species evolved and thrive.

Ultimately, advances in water conservation and technology will enable many regions in California to become largely self-sufficient for water, but this will not occur within the timeframe left to save the Delta.

Moving Past the Debate

The concept of an alternate water conveyance system in the Delta is not new and has been controversial since it was first proposed in the early 1980s. However, today there is broad recognition that an alternate way of moving water could serve dual purposes to restore the Delta ecosystem and provide a reliable water supply to other parts of California, if done right.

The Bay Delta Conservation Plan has evolved significantly since 2009, when we publicly supported the need for a new system of moving water through California if the system was required to be operated in a way that improved ecological conditions in the Delta. Through the intervening years the Conservancy has not taken a position either in support of or in opposition to the BDCP. Instead, the Conservancy has been supportive of the Bay Delta Conservation Planning process as potentially a way to move toward a solution and has been engaged in the ongoing Bay Delta Conservation Planning process with the goal of ensuring that a final plan: 

  • Provides a basis for better long-term ecological conditions in the Delta, including providing water at the right times in the right amounts to help recover crashing fish populations
  • Includes a strong monitoring and science program to guide operations of any new tunnels
  • Protects the remaining natural habitat in the Sacramento and San Joaquin valleys and secures the water and wetlands necessary for healthy fisheries and bird migration across the Central Valley
  • Includes investments in flood safety in the Delta, addressing flood conditions that will be more likely in California as we experience larger and less predictable storms due to our changing climate

Unfortunately, draft plans released in August 2013 showed that twin tunnels used for moving water under, rather than through, the Delta would be placed below Staten Island and would impact vitally important habitat for wintering sandhill cranes. Fifteen percent of the greater sandhill cranes in the Central Valley winter on Staten Island, which was acquired by The Nature Conservancy in 2001 in order to protect crane habitat provided by wildlife-friendly agriculture, and we are committed to this outcome.

Based on scientific analysis and conservation planning, we do not believe the current BDCP will meet the defined conservation goals and objectives, and construction of the tunnels could undermine existing conservation efforts and legal responsibilities we hold as the land owner of Staten Island.

We continue to support the dual goals of improving habitat conditions for endangered fisheries, migratory birds and other wildlife in the Delta while reducing reliance on the Delta as the source of California’s water supply. However, we cannot support the BDCP as written.