Maritime Boundary Project

Maritime boundaries for the United States are determined from the official U.S. baseline, recognized as the low-water line along the coast as marked on the official U.S. nautical charts in accordance with the articles of the Law of the Sea. Traditionally, boundaries have been constructed by hand by cartographers from the depiction of the low water line on Coast Survey nautical charts and drawn through a series of arcs at the appropriate distances from the baseline. These arcs are then reviewed and approved by the ad hoc Committee on the U.S. Baseline, chaired by the Department of State (DOS), prior to publication of the new maritime limit on the new chart edition.

New production processes, digital products, and the increasing public demand for access to the geographic baseline points necessitate the use of new technology to maintain the official U.S. baseline and determine maritime boundaries. Incorporating new raster/paper compilation methods, the post compilation time between adding new information to the chart base and printing has decreased from 6 - 8 weeks to under 2 weeks. This time interval is not sufficient to gain approval of the U.S. Baseline Committee for changes to the maritime boundaries using traditional compilation methods. Through the continued improvement of raster compilation methods pioneered by the Office of Coast Survey (OCS), this time difference will continue to decrease. In addition, there is an increase in demand for vector maritime boundaries and digital baseline points for use in natural resource calculations, enforcement of state and Federal laws, and in the Electronic Nautical Chart (ENC) product for ECDIS systems.

At the same time, the Mineral Management Service (MMS) has requirements for a digital baseline and digitally determined boundaries for enforcement of the U.S. Submerged Land Act. In 1997, OCS and MMS entered into a Memorandum of Understanding to produce, quality assure and maintain a digital baseline for use by both agencies in accomplishing their respective missions.

During 1998, the Cartographic and Geospatial Technology Program of the Coast Survey Development Laboratory provided the necessary tools for quality assuring a digital baseline against the current raster/paper images, software to produce vector and raster maritime boundaries from the resultant accepted digital baseline, and processes to incorporate the approved digital boundaries into the traditional and electronic nautical products which OCS produces.

CGTP is developing a GIS infrastructure for OCS' Geographer's office to maintain the digital baseline for the U.S. Maritime Boundary. While the original baseline points were scaled off the nautical charts, the updates will be maintained by OCS production cartographers during source assessment and compilation for new shoreline To date, the east coast shoreline data was successfully converted into a spatial database and loaded in the ArcView and ArcInfo GIS system and is being evaluated. An AML script was developed to "buffer" the shoreline control points into a series of arc circles to create the 3nm and 12nm Maritime boundary.

Using Geographic Information System technology, OCS’ full suite of adjusted raster images, and algorithms developed through interagency cooperation (OCS, MMS, and DOS) and existing raster and vector compilation processes, OCS will be able to provide accurate and timely digital maritime boundaries.