Alaska Cadastral Data
Geographic Information System (GIS) Data and Maps
The Mapping & Boundary Branch performs mathematical offshore boundary location computations and prepares Official Protraction Diagrams (OPDs), and Supplemental Official OCS Block Diagrams (SOBDs) depicting OCS Block information, the Submerged Lands Act Boundary (aka - State Seaward Boundary), Limit of "8(g) Zone", the Continental Shelf Boundary (CSB) which marks the limit of U.S. jurisdiction for offshore mineral development, and corresponding area measurements. The analytical procedures employed and the computer programs utilized to perform various offshore boundary geometric computations are described in OCS Report MMS 99-0006.
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A standard OPD is 1 degree in latitude by 2 degrees in longitude (at lower latitudes: 0 - 48 degrees). At higher latitudes (48 - 75 degrees) such as Alaska and northern Washington, OPDs are 3 degrees wide. OPD limits usually approximate the standard 1:250,000 scale U.S. Geological Survey topographic map series. The OPDs are numbered using the United Nations International Map of the World Numbering System. OPD names usually coincide with standard topographic sheet names when diagrams include land areas. OPD sheet names relate to land features, or to hydrographic features contained within the limits of the diagram. Shoreline planimetric detail is shown when it falls within the limits of a diagram. Older OPDs were prepared on mylar with manual cartographic methods and then scanned into Adobe .pdf files. Newer OPDs were prepared electronically and converted to Adobe .pdf files.
A Supplemental Official OCS Block Diagram (SOBD) is prepared for each block intersected by an offshore boundary (Submerged Lands Act Boundary, Limit of "8(g) Zone", National Marine Sanctuaries, etc.). Note that not all OPDs contain such boundaries, therefore not all OPDs have SOBDs associated with them. All the SOBDs for a given OPD are zipped into a single file for downloading. The zip files will contain the most recent version, but older historic versions may also be included for reference. For the purpose of future Lease Sales always be sure to use the most recent version.
Composite Block Diagrams (CBDs) show NAD 27 lease information portrayed on the NAD 83 cadastre. Not all OPDs have CBDs associated with them.
Supplemental Official Lease Diagrams (SOLDs) identify areas within a block or several adjacent blocks that have been combined into a single bidding unit for a specific lease sale. The diagram includes boundary intersections, baseline arc centers, and areas. Not all OPDs have SOLDs associated with them.
Image File Formats
The most current approved revision for each Alaska Region OPD and SOBD may be viewed and downloaded from the list below. OPDs are offered in Adobe (.pdf) format. SOBDs are available as Adobe (.pdf) files that have been compressed with WINZIP. Adobe (.pdf) files may be viewed with the free Adobe Acrobat reader.
The various boundaries are also offered as ESRI ArcGIS shapefiles. Shapefiles can be viewed with the free ArcGIS Explorer Desktop viewer, ArcGIS, or a variety of other GIS systems. The shape files have been zipped using WinZip.
Note: The precise coordinates of a GIS file can be altered slightly by various GIS functions. For that reason, these GIS files are not an Official Record for BOEM offshore boundaries. Only the coordinates shown on Official OPDs, CBDs, and SOBDs constitute an Official Record for offshore coordinate values.
Note: OPDs have not yet been published for all Alaska offshore areas and only the current versions of published OPDs are available from this site. Please contact the Alaska Region if you are looking for NAD 27, or older superseded NAD 83 versions.
All coordinates are in NAD 83. Alaska Region leases and cadastre data from before 1994 were mapped using the North American Datum of 1927 (NAD 27). These new NAD 83 files do not represent a conversion, but rather a complete re-grid. For further details, see Project Plan for Implementing NAD 83 in the Bureau of Ocean Energy Management:
Planning Area Acreage Statistics as of 10/02/2008
Planning Area Descriptions as of 04/2013
Additional Alaska Data Sources