Dataset was built over years based on a variety of sources and ongoing incidents during the period in which the dataset steward was in the Delta Levees Program. Consequently, it primarily consists of levee failures in the Delta, plus additional levee failures mapped by the State Office of Emergency Services for the 1983, 1986, 1995, and 1997 floods throughout the Central Valley.

Dataset was assembled over many years by Joel Dudas from DWR, first while in the Delta Levees Program, and later in the Division of Engineering/Geodetic Branch. Various primary sources were utilized, including: 1) a Valley-wide set put together by FEMA, the Corps, & state OES, using the contracting services of Montgomery Watson Associates, for the 1983, 1986, 1995, and 1997 floods. 2) An older map from the early 1990's that was developed by Carl Hauge when he was a part of DWR's Central District that showed Delta levee breaks up until 1986. 3) A file that belonged to DWR Delta Levees (originally compiled when Delta Levees was part of Central District) by Ron Landingham and stored on Bernoulli disks. 4) J. Dudas observations while at DWR up until 2017. J. Dudas also refined many of the point locations in the other datasets by using historic aerial photography, as well as by identifying the scour ponds that correspond to the breaches in order to improve the locational quality. Delta reclamation district engineers also provided some of the information (particularly with respect to historic causes) in addition to verifying the DWR data.

An important point of clarification is that DWR Division of Flood Management has other sources for historic levee failures (including the ULE/NULE and California Levee Databases) that are not included here. There are some overlaps, but there are also significant omissions and or discrepancies between the various dataset sources. Synchronization of the datasets – and the work it would take to do that – has been considered but is not currently feasible. So the candidate dataset is to be promoted as a useful stopgap until such time as better historic definition can be performed.