Data contains historical polygons of in-channel islands within the Sacramento San Joaquin Delta. Data consists of merged datasets from 1929, 1940, 1949, 1952, 1995, 2002, and 2017. The 2017 polygons are digitized from the 2017 Delta LiDAR imagery by the Division of Engineering, Geomatics Branch, Geospatial Data Support Section. The older pre-2017 polygons were all digitized by staff in the Delta Levees Program. Data can be queried for a single year or date range using the 'Year' field. Historical data was compiled and merged from datasets provided by the Delta Levees program. Data coverage differs between years. Absences or gaps in historical data may occur. Older acquisitions generally have a smaller footprint than recent imagery acquisitions. The 2017 in-channel islands cover the Legal Delta, and also include Chipps Island. The associated data are considered DWR enterprise GIS data, which meet all appropriate requirements of the DWR Spatial Data Standards, specifically the DWR Spatial Data Standard version 3.1, dated September 11, 2019. DWR makes no warranties or guarantees — either expressed or implied — as to the completeness, accuracy, or correctness of the data. DWR neither accepts nor assumes liability arising from or for any incorrect, incomplete, or misleading subject data. Comments, problems, improvements, updates, or suggestions should be forwarded to the official GIS steward as available and appropriate at gis@water.ca.gov.