In the Delta Anatomy Mapping Project, all levee anatomies were delineated using slope grids built from available 2007 Delta LIDAR data points. LIDAR data points were converted to digital elevation models and subsequently into slope grids. Thresholds were identified that capture the levee crown, levee landside, levee waterside, ramps and toe ditches. Visual interpretations of slope thresholds were used in conjunction with heads-up digitizing to maintain smooth boundaries at a scale of 1:550. The delineation thresholds were derived from a combination of mapping scale, slope grid resolution and slope thresholds used for each anatomy classification. All anatomy has gone through internal quality control processes to ensure a minimum accuracy of +/- 3 feet.

Anatomy data was further reviewed and tested by DWR for compliance with an interpretive mapping standard of 80% accuracy. Once the levee anatomy was created and accepted, isolation and export of the levee crown was used in conjucture with ET Geowizards to collapse the crown to a singular centerline which details the levee route. This data depicts the levee anatomy at the time of the LiDAR survey (2007) and are only accurate for that time. Users should be aware that temporal changes may have occurred since this data set was created and some parts of this data may no longer represent actual surface conditions. Changes in some linework and attribution were performed by CA DWR Division of Engineering in September, 2018, and current version was posted to DWR GIS Atlas at that time