What is the Delta?

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Detailed Description

This short video is intended to serve as an introduction to the Sacramento and San Joaquin Delta, and is the first in a series of four short videos highlighting USGS science in the San Francisco Bay and Sacramento-San Joaquin Delta Estuary. This video serves to orient the viewer to physical characteristics of the Delta, the challenges facing it, and the work the USGS is doing, in coordination with our partners, to understand and characterize the Delta ecosystem.


Date Taken:

Length: 00:03:04

Location Taken: Sacramento, CA, US


When it comes to water in California there is no more 
important single region than the Sacramento-San Joaquin Delta.  

The Delta is a major hub for freshwater in California.

It covers more than a thousand square miles, and supplies water
for about 25 million people. 

The Delta is formed by the confluence of the Sacramento 
and San Joaquin rivers. 

When wild long ago, the region was rich with wildlife  and wetlands. 

In the 1800s, levees were built that converted the landscape for agriculture... resulting in one of the country's most productive farming regions. 

Now, more than a thousand miles of levees transverse the Delta. 

Twice each day, tides push salt water west to east through the Golden Gate into the Delta. 

Fresh water enters the Delta and then typically flows from east to west, moving through the leveed channels to San Pablo Bay, San Francisco Bay and eventually the Pacific Ocean. 

When needed, a large portion of the fresh water entering the Delta is diverted from the Sacramento River at an engineered water gateway called the Delta Cross Channel.
Once diverted, the water moves south though leveed canals toward the pumps where it is pumped into the California Aqueduct and the Delta-Mendota Canal for use in agriculture, and for use by people in central and southern California.

Challenges, such as  increasing demands on the available water for agriculture urban and ecological needs along with an aging levee infrastructure subsided islands decreased water quality saltwater intrusion into the Delta and a changing climate combine to create a complex system where there are no simple solutions.  

Integrating research and monitoring into the management of the Bay Delta ecosystem provides a framework for using the best available science to cope with risks and uncertainty. 

USGS scientists, in a wide variety of scientific disciplines seek to understand how the Bay-Delta works to monitor changes in water flow and quality as well as ecosystem functions over time and to provide information and decision support tools for the management of California's water system.  

Through the work of these scientists USGS contributes essential scientific support to managers and policymakers striving to address California's water challenges and support a vibrant Bay-Delta ecosystem community and economy.