This dataset is a partial rendition of the CalGEM (formerly the California Division of Oil, Gas, and Geothermal Resources) publication called California Oil and Gas Fields Volume I: North and East Central California (1973 with 1978 supplement), Volume II: South, Central Coastal and Offshore California (1974), & Volume III: Northern California (1981).  The dataset illustrates some areas in each Oil & Gas field where oil or gas production occurred and are deemed exempt for injection per the Primacy Agreement between US EPA and CalGEM.  These "Productive areas" are depicted in two ways in the Volumes: (1) by inference from well symbols placed on the map illustrations,.(2) by shaded areas on the map illustrations.  Only the illustrated shaded areas as depicted in the historical publications are represented in this dataset.  Geologic attributes detailing the Productive Zones (Formation, Zone, and Discovery Date) are supplied for each Productive area shape.  Volume III updated certain Productive areas in Northern California listed in Volume I.  The update included  revised Formation Zones and expanded Productive areas.  In cases where  the geologic nomenclature attributes in Volume I differ from those in a corresponding Productive area in Volume III, the Formation Zones nomenclature in the later Volume are considered to be definitive.  This updated dataset was published 2-28-2020 and supersedes all earlier versions. 

Volumes I, II, and III are also available in PDF format.  Recommended map display scale is 1:100,000.