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Department of the Interior
Dataset Description
Aliquots are generated from Outer Continental Shelf (OCS) blocks by subdividing each block into 16ths, and this further subdivision allows for more detailed boundary delineation in offshore energy leasing. These polygons are clipped to the Submerged Land Act Boundary and Continental Shelf Boundaries. The aliquots use a letter designation in addition to their parent protraction number and OCS block number (e.g., NK18-02, 6822F). A full OCS block is 4800 x 4800 meters, while an aliquot measures 1200 x 1200 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 Official Protraction Aliquot Diagram (OPAD) should be used for official or legal purposes.
These data were created in the applicable NAD83 UTM or NAD27 UTM/SPCS Projection and re-projected to GCS WGS84 (EPSG 4326) for management in BOEM's enterprise GIS. However, this service in this collection has been published in WGS 1984 Web Mercator Auxiliary Sphere (EPSG 3857). Because GIS projection and topology functions can change or generalize coordinates, these data are NOT an OFFICIAL record for the exact boundaries. These data are to be used for Cartographic purposes only and should not be used to calculate area.
Organization: Department of the Interior
Organization URL: https://catalog.data.gov/organization/doi
Last updated: 2026-03-31T00:00:00Z
Tags: Administrative, Alaska, Aliquot 16ths, Atlantic, BDS, BOEM, Boundary Delineation System, Bureau of Ocean Energy Management, Cadastre Theme, Conventional Energy, Energy, Gas, Gulf, ISO 19115, Marine Minerals, OCS, OMC, OPDs, Official Protraction Diagrams, Offshore Marine Cadastre, Oil, Outer Continental Shelf, Pacific, Renewable Energy, SOBDs, Supplemental Official Block Diagrams, U.S. Territories, Wind