Unlike on shore boundaries, most marine boundaries are not marked with monuments or fences. But like a monument or fence, marine boundaries DO require maintenance! Poorly maintained boundaries can impair enforcement of environmental, fishing, and other regulations along that boundary. Further, it must be recognized that no agency places a marine boundary that doesn’t affect multiple other agencies. This paper presents a brief primer on marine boundaries, followed by 3 case studies.

Primer on Marine Boundaries

Most marine boundaries are projected from a baseline, which consists of discrete points selected along the shoreline. The figure above illustrates our first problem – Where is the shoreline? USGS topo maps typically display either the mean sea level or the mean high water line, while NOAA nautical charts typically show the mean lowest low water line. (Always check your map to see which datum was used). Various states use different water levels to mark the division between private lands and state controlled territory. Note that federal offshore boundaries are measured from the mean lowest low water line.

Federal offshore limits and boundaries include:

• The State Seaward Boundary - The Submerged Lands Act of 1953 (43 USC 1301) grants most coastal states jurisdiction out to 3 nautical miles.
• Revenue Sharing Line – This line, also referred to the "limit of 8g" extends 3 nautical miles beyond the State Seaward Boundary. Revenues generated from resources such as oil and gas within this area are shared between the federal government and the coastal state. Note that these two lines are unique to the US. In most countries, ALL offshore territory is controlled by the federal government.
• Territorial Sea – This line was previously at 3 nautical miles, but was moved to 12 nautical miles by Presidential Proclamation 5928 in 1988, in accordance with the United Nations Convention on the Law of the Sea (UNCLOS). The U.S. claims sovereignty within this line from the air space down through the water column and into the subsoil.
• Contiguous Zone – Established by Presidential Proclamation 7219, in 1999, this 24 nautical mile buffer grants the U.S. "The . . . control necessary to prevent infringement of it’s customs, fiscal, immigration or sanitary laws and regulations within it’s territory or territorial sea."
• Exclusive Economic Zone (EEZ) – Created by Presidential Proclamation 5030 in 1983, the EEZ claims for the U.S. exclusive rights to economic resources such as oil, and gas out to 200 nautical miles.
• Article 76 Claims – Article 76 of the most recent Law of the Sea Convention allows countries to claim resources out to a maximum 350 nautical miles, depending upon the configuration of the continental shelf.

Note that all these boundaries are measured from the baseline points, which are established along the Mean Lower Low Water (MLLW) line, which includes rocks and islands. Remember too that with erosion and accretion, the coastline can move. When that happens, the baseline and associated boundaries will all move with it. Finally remember that all these boundaries are in nautical miles. A nautical miles equals one minute of latitude at the equator, or 6080.2 feet, which is not the same as a statute mile commonly used on land – 5280 feet.

Other offshore boundaries would include National Parks, Marine Sanctuaries, Lease Blocks, etc.

Case Study 1 – The Virgin Islands Coral park system in the U.S. Virgin Islands appeared to be one way to accomplish this.

The Clinton Administration was looking for ways to provide greater protection to the Nation’s coral reefs. Enlarging the boundaries of the existing /P>

Obviously, the first step for any boundary development is to establish the baseline along the coast. The United Nations Convention on the Law of the Sea, Article 5 states "…the normal baseline for measuring the breadth of the territorial sea is the low water line along the coast as marked on large-scale charts officially recognized by the coastal State. " For the U.S., that would be the NOAA Nautical Charts. Selecting the baseline simply requires that the seaward most points along the coast, including rocks and islands, be identified, and coordinates obtained (usually through digitizing). A problem arises with "low water features" indicated on the charts with an asterisk. In the example shown, one asterisk is indicated in parentheses as being 2 feet above datum (MLLW). It can be included in the baseline. Another rock is indicated as being 1 foot below datum. It does not qualify as a baseline point. But what about the other rocks that are undesignated? These need to be field checked.

Once the baseline was established, the various boundaries could be calculated. As shown to the right, those boundaries include: the Territorial Submerged Lands Act boundary at three nautical miles – shown in solid red, the Territorial Sea boundary at 12 nautical miles – shown in dashed red, the equidistant line separating Puerto Rico and the Virgin Islands –shown in black, and the International boundary separating the U.S. and British Virgin Islands – shown in blue. Coordinates for the international boundary had already been published by the U.S. Department of State in the Federal Register.

While The Submerged Lands Act of 1953 granted the three nautical mile area to the states, it was a separate act – The Territorial Submerged Lands Act (TSLA) signed on October 5, 1974 – that transferred control of the three nautical mile area to the territories. But a careful reading of that act reveals this clause "There are excepted from the transfer made by subsection (a) hereof - … all submerged lands adjacent to property owned by the United States above the line of mean high tide;…" That would indicate that there may be some areas within the 3 nautical mile line that were retained under U.S. jurisdiction and were not relinquished to the territories. But to our knowledge, in over 25 years since the enactment of the TSLA, no one had ever mapped out the affected areas.

Mapping those areas first required a careful search of the land records to see which partials were owned by the U.S. government at the date of the enactment of the TSLA – October 5, 1974. Once those areas were identified, and precise coordinates determined, equidistant lines could be calculated to separate federal areas from areas under territorial jurisdiction. This map of St Johns shows Federal areas in blue. Territorial areas are shown in tan. Previously existing offshore parks are shown in green crosshatch. Acres and hectares for each area are also displayed.

Having established federal ownership of these areas made it possible to then convert them to National Monument Status, which President Clinton did on January 17, 2001, with Presidential Proclamation 7399 and 7392. These Executive orders are still under review by the Government Accounting Office, however it appears that in this case careful attention to boundary issues may prevail in bring an expanded park boundary, and greater protection to these delicate coral resources.

Like The Virgin Islands National Monument, Glacier Bay National Park has both an onshore and offshore component. The Offshore component of Glacier Bay National Park is now being contested in the U.S. Supreme Court (see No. 128, Original State of Alaska, Plaintiff v. United States of America, available at http://www.usdoj.gov/osg/briefs/1999/1original/0128.resptomotforleave.html. In this case:

But even if the Park Service is able to keep it’s offshore property after this case is settled, questions remain with the boundary. That boundary, as set forth by Executive Order [No. 2330, April 18, 1939-53 Stat. 2534] states that the boundary goes from :

This description raises a number of questions. What is meant by the term "the general contour of the coast"? Is it a high water line? A low water line? Does it include rocks and islands? The NPS map GLBA-90,004 shows the original Park Service interpretation for this line. What further complicates the issue is a Federal Register Notice published by the National Park Service on September 30, 1992. This notice is in conflict with both the earlier Executive Order and map GLBA-90,004. The Federal Register Notice stated " … Thence due west, 3 miles to a point on the line demarking the Territorial Sea of the United States …". If one uses the Territorial Sea Line then one has to use rocks and islands to determine the boundary. The map below depicts the Park boundary (taken from map GLBA-90,004) in green and the SLA 3 nautical mile line (as calculated by MMS) in red. It is clear that rocks and islands were not originally used by NPS in determining the Park’s boundary. Also at issue here is the depiction of a median line through a number of straits within Cross Sound. To our knowledge the Park Service has never issued official coordinates describing this boundary.

Case Study 3 – the Florida Keys

In order to give greater protection to the marine resources of the Florida Keys, especially those that are not already protected by the existing patchwork of state and federal parks in the area, NOAA has established the Florida Keys National Marine sanctuary. This action will require other agencies, such as the Minerals Management Service, to withdraw the affected area from consideration for oil and gas development. Unfortunately, NOAA has been unable to supply a complete set of coordinates for the Sanctuary. They have a gap where the sanctuary closes against the existing boundary for the Everglades National Park. This is because they have been unable to get precise coordinates for that boundary from NPS. Until they are able to get those coordinates NOAA will be unable to finish their work on the Sanctuary, and MMS will be unable to complete their withdrawals for the area within their Cadastre. All of this helps to illustrate the point that no one places a boundary out there that doesn’t affect everyone else.

Clearly, it is not easy for GIS users to convert legal descriptions of boundaries into precise coordinates needed to display them in GIS systems, especially when those legal descriptions are vague or inconsistent. Ambiguities in boundary locations could impede enforcement of those boundaries. Finally, ambiguous boundaries controlled by one entity can also negatively affect other agencies in performing their duties.

To deal with numerous issues such as these, the Marine Boundary Working Group was formed in 2001 under the Federal Geographic Data Committee. It includes representatives from nearly every federal agency (including NPS) which either creates or uses offshore boundaries. As stated on their web site (http://www.csc.noaa.gov/mbwg/htm/overview.htm)

Precise, unambiguous, offshore boundaries can be an asset in protecting the valuable resources that have been placed under the care of the National Park Service. Failing to properly maintain these boundaries can negatively affect NPS enforcement of those boundaries, and also impedes the work of other federal agencies. The Marine Boundary Working Group is a valuable resource in achieving these goals.