The bathymetry of the Sacramento-San Joaquin Delta affects the flow of water and sediment throughout the system and is a basic control on levee stability, habitat distribution, and water quality. Delta bathymetry is dynamic, responding to both natural forces and human activities. Assessment of future Delta conditions is aided by understanding how its bathymetry has changed in the past. This pilot study explores historic bathymetric change in the Delta. The earliest comprehensive surveys that covered a large portion of the Delta were conducted in the 1930s by the U.S. Coast and Geodetic Survey, the precursor to the National Oceanic and Atmospheric Administration. These historic surveys are compared to recent surveys conducted by the California Department of Water Resources and others to document how sedimentation and erosion have changed the Delta. We selected regions for the pilot study based on availability of data, critical habitats, and importance to fellow researchers who are trying to predict future changes to the Delta. As the Delta is altered though both natural processes and human development, understanding how the bathymetry has changed will help improve predictive models of the system.