OCS Blocks - Alaska Region

Outer Continental Shelf (OCS) blocks serve as the legal definition for BOEM offshore boundary coordinates used to define small geographic areas within an Official Protraction Diagram (OPD) for leasing and administrative purposes. These polygons are clipped to the Submerged Land Act Boundary and Continental Shelf Boundaries. OCS blocks relate back to individual Official Protraction Diagrams (OPDs) and are not uniquely numbered. A block is uniquely described by the Protraction Number and Block Number (e.g., NK18-02, Block 6822). A full OCS block is 4800 x 4800 meters. Smaller, clipped aliquots are found along the Federal/State OCS boundary and along UTM zone borders. Only the most recently published paper or PDF versions of the OPDs or Supplemental Official Block Diagrams (SOBDs) should be used for official or legal purposes.

This data was created in the applicable NAD83 UTM Projection and re-projected to NAD83 Geographic. Because GIS projection and topology functions can change or generalize coordinates, these GIS files are NOT an OFFICIAL record for the exact boundaries. These files are to be used for Cartographic purposes only. This data should not be used to calculate area.