How Do I Know When I Am in Federal Waters?

State & Federal Offshore Waters Explained

By Captain Irvin "Sandy" Dares

A frequently asked question is how to determine, when in the Gulf of Mexico, if you are in state or federal waters. This is important because some federal fishing regulations differ from state laws. For instance, red drum may be taken and possessed in Louisiana waters, both inshore and offshore; however, the possession of red drum in federal waters is prohibited. Some shrimp regulations are also different in federal waters. While Louisiana laws attempt to mirror many federal regulations in state law, it is not always done.

The first thing to understand is that the boundary between offshore Louisiana state waters and offshore federal waters is a line called the three-mile nautical line. Some states, notably Texas and Florida, have boundary lines of nine nautical miles. The three-mile line is the limit of Louisiana's state jurisdiction under the Submerged Lands Act (P.L. 83-31; 67 Stat. 29, March 22, 1953).

Another very important point is that the three-mile line is not always three miles from the beach. There are a variety of reasons for discrepancies, including coastal erosion and the legal definition of the line. For instance, in the Grand Isle area this line runs straight across a section of the gulf instead of following the contours of the shoreline. In this area, the boundary may lie several miles from the beach. The irregular contours and fluid nature of the Louisiana coastline and the Mississippi River delta shorelines also create a unique set of problems.

The primary means of determining whether you are in Louisiana or federal offshore waters is to use a nautical chart. The National Oceanographic and Atmospheric Administration publishes these charts, some of which show the three-mile line. For example, chart number 11361 covers the mouth of the Mississippi River. These charts have latitude and longitude scales, as well as LORAN scales, so both LORAN and GPS instruments may be used to determine your position in relation to the state-federal line.