This is a region dataset delineating the areas of offshore Louisiana and Texas having Regional Response Team VI (RRT 6) pre-approval for the use of dispersants to break up an oil spill. This area is defined as that area of no less than 10 meters depth and at least three nautical miles from the nearest shoreline, out to the limit of the Exclusive Economic Zone. Three nautical miles from the nearest shoreline for Louisiana corresponds to the state's territorial limits. This data set is bounded on the west by the Galveston Marine Safety Office zone and on the east by the Mobile Marine Safety Office zone. The attributes of the boundary arcs indicate the source of each section of the boundary.
The data layer can be used as a guide for the Federal On Scene Coordinator (FOSC), the Louisiana Oil Spill Coordinator's Office, the Regional Response Team VI (RRT 6), and oil spill response organizations in the event of an oil spill emergency. During such an event the clean-up methods of mechanical, in-situ burn, and dispersant are all options. The establishment of preapproved areas for these methods allows the OSC to quickly approve their application in non-excluded areas. These data were derived from seven different sources, and as a result there are some areas that are less reliable than others. In particular, the area near the north end of the Chandeleur Islands <URL:zongeog3dbdis2.gif> is an approximation, however the delineation is conservative in that area, so as to exclude, rather than include the area in question for pre-approval designation. Most of the remainder of the boundary, which is represented by data derived from NOAA point depths is relative to Mean Low Gulf conditions, hence is also conservative based on the source data.
The user should be aware that meteorological events such as hurricanes may alter the position of the 10m depth line delineating the shoreward limit of the dispersant preapproval zone or may have already have already altered the position from that represented in these data. Furthermore, geomorphological processes due to sediment load are causing landward migration of isocontours at a rate of about 25 meters per year in the Mississippi River Delta Plain area (east and west of where the Mississippi empties out into the Gulf). Because these data are based on historical NOAA charts, the effects of this migration have not been captured.
Time Period of Content
Time Period Information
Maintenance and Update Frequency
West Bounding Coordinate
East Bounding Coordinate
North Bounding Coordinate
South Bounding Coordinate
pre approved dispersant line
These unaltered data may not be redistributed without all of the elements of the metadata listed in the Supplemental_Information section of this metadata document. It is recommended that third parties wishing to use these data obtain them from the Distributor listed in this metadata document. If these data are altered or incorporated into another dataset, they are not to be redistributed without also: altering the name of the dataset, including a Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998) compliant metadata file that describes the dataset and reflects the alteration steps that makes the new dataset different from this one, and citing this dataset in the metadata as a source for the altered dataset using the source citation specified below.
If these digital data are used in the production of a report or in the compilation of a standalone printed map, then this dataset is to be cited in the report or on the map using the source citation specified below.
Point of Contact
Contact Person Primary
Texas General Land Office
1700 North Congress Ave., Rm 970
State or Province
Contact Voice Telephone
Data Set Credit
Texas General Land Office
Native Data Set Environment
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 184.108.40.2062
Data Quality Information
Logical Consistency Report
Topological and labeling tests, and attribute statistics were obtained with a quality assurance AML (qa_report.aml). This report is used to expose inconsistencies and problems in the data and its attributes, and to verify correction of those errors when corrections are possible. No labeling or topological errors were found.
As mentioned in the Purpose, there is an area of this data set that is less reliable than others. This is at the north end of the Chandeleur Islands where the boundary is defined by the TerrainBase data derived 10 meter depth line. It was necessary to use this data to patch a gap in the 10 meter depth line that was present in the NOAA point depth derived bathymetry line. The TerrainBase contour does not match well to the NOAA 10m line, so a line had to be constructed between the two. The NOAA data is based on a much denser depth sampling so is believed to be the more reliable of the two. An ETOPO5 derived 10m depth contour agreed closely with the TerrainBase contour; this is not surprising because ETOPO5 data was one of the sources used to build the TerrainBase source data.
National Ocean Service GEODAS was also examined for sounding data in the Chandeleur Islands but no surveys cover the area of interest in the appropriate depth range.
Marine Spill Response Corporation (MSRC), and Region VI Regional Repsonse Team (RRT), 19960501, OSC Preapproved Dispersant Use Manual.
Type of Source Media
description of dispersant preapproval zone
Service, Minerals Management , unpublished, 'Exclusive Economic Zone Line in the Gulf of Mexico'
Type of Source Media
delineation of most oceanward boundary of of dispersant pre-approval area, the Exclusive Economic Zone, at a nominal 200 nautical miles from the shoreline.
US Government Printing Office, 1997, 33 CFR Ch1 (7-1-97) section 3.40-15, section 3.40-17, section 3.40-30.