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.
A
standard Official
Protraction Diagrams (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.
SOBD Images
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. The zip files offered here contains
only current NAD 83 SOBDS. The historic (outdated) SOBDs can
be obtained by contacting the Mapping & Boundary Branch. All
future activities will be based on the most current SOBDs.
Image File Formats
The most
current approved revision for each Atlantic 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.
All Current Published Atlantic Region NAD 83
OPDs and SOBDs
All current, published NAD 83
OPDs for the Atlantic Region in Adobe (.pdf) format
have been zipped together in two files. For details
see the
metadata.
The various boundaries are also offered as ESRI ArcGIS
shapefiles. Shapefiles can be viewed with the free
ArcGIS Explorerviewer,
ArcGIS, or a variety of
other GIS systems. The shapefiles 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 BOEMRE offshore
boundaries. Only the coordinates shown on Official OPDs, and
SOBDs constitute an Official Record for offshore coordinate
values.
The
baseline point file used (along with
the baseline tangent file) to
project the boundaries shown on
existing/published OPDs. See
detailed metadataBrowse-Graphic
Tangents (primarily Bay Closing
Lines) used along with baseline
points to project the boundaries on
existing/published OPDs. See
detailed metadataBrowse-Graphic
