Alaska Cadastral Data
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
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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
NOTE: OPDs that show the Submerged Lands Act and Section 8(g) Zone boundaries do not reflect post-2010 shoreline changes. The Submerged Lands Act and 8(g) Zone boundaries in the Beaufort Sea and the Chukchi Sea were permanently immobilized by the U.S. Supreme Court on June 29, 2000.
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.
NOTE: SOBDs do not reflect post-2010 shoreline changes. The Submerged Lands Act and 8(g) Zone boundaries in the Beaufort Sea and the Chukchi Sea were permanently immobilized by the U.S. Supreme Court on June 29, 2000.
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
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.
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:
Area Acreage Statistics as of 10/02/2008
Area Descriptions as of 04/2013
Additional Alaska Data Sources