The Sacramento-San Joaquin Delta is the hub of the State of California's water supply and distribution system. Runoff is captured in the northern part of the State and later released and transported though the Delta to State and Federal export facilities located at the southern boundary of the Delta near Tracy. The water is then pumped into the California Aqueduct and Delta-Mendota Canal for use south of the Delta, including the Los Angeles area.

The exportation of water from the Delta is thought to have created several problems within the estuary, primarily with regard to declining fish populations and degradation of water quality; the drinking water supply for 20 million Californians passes through the Delta.

To solve these problems, a knowledge of the hydrodynamics of the Delta is required. There has been a lack of measured flow data thoughout the Delta because the flows are very dynamic due to tides that propagate from San Francisco Bay. Over the last several years, the USGS has been using acoustic technology to measure the flows in the Delta.

Measured flow data are needed:

• to gain an understanding of the hydrodynamics of the Delta,
• to determine the quantity of water flowing from the Delta into San Francisco Bay, and
• to calibrate and validate flow and transport models of the Delta.