On behalf of Sayer Regan & Thayer of Sayer Regan & Thayer, LLP posted on Tuesday, December 15, 2020.

It’s difficult to imagine boundaries when you’re in open waters. It all looks the same, wave after wave, with very few visual indicators of the boundaries between State and Federal waters.
Sometimes regulations remain consistent between state and federal waters, but sometimes significant differences exist, with pricey penalties for violations. Accordingly, it’s critical to know where the lines are, even when you can’t see them. Many times, legal disputes arise over activities conducted on one side of a line or the other these disputes are generally handled under the umbrella of admiralty and maritime law.


State boundaries in open waters of the United States were first defined in the 1940s over concerns about rights for oil under submerged lands. In a 1947 landmark case, the U.S. Supreme Court ruled against the state of California, saying the federal government held rights in all submerged lands of the Pacific seaward of the low-water mark. The U.S. Supreme Court gave a similar ruling against Louisiana and Texas.
Congress then created the Submerged Lands Act of 1953, which declared that states owned the submerged lands, and the natural resources within, seaward out to three nautical miles. In some cases, a state’s boundary may be extended if beyond the standard three nautical miles from the coast if that extension of rights was declared before achieving statehood. It is worth noting that a nautical mile is slightly longer than a statutory mile.

State/federal boundary lines are marked as the natural resource line on NOAA nautical charts and those lines are usually present on most marine GPS units. It is essential that a mariner be aware of his or her vessels position relative to the State / Federal waters boundary line in order to avoid running afoul of regulatory restrictions.

Contact Sayer Regan & Thayer for Your Maritime Law Needs

To learn more about the lines between federal and state waters, particularly as they relate to Rhode Island waters, please contact us for your free initial consultation. We have the expertise to address all areas of admiralty or maritime law cases. Our team of lawyers includes a RYA/MCA Yacht-Master and U.S.C.G. Master, a Maritime Professional Instructor, as well as a former America’s Cup sailor. Our lawyers have written and lectured on a wide range of admiralty and maritime law issues and remain actively involved in the yachting and commercial maritime communities.

These materials have been prepared by SRT for informational purposes only and are not intended and should not be construed as legal advice.