The U.S. Supreme Court is scheduled to hear arguments during the first week of October to determine who owns the waters of the Potomac River, deciding whether Maryland can prevent Virginia from drawing water from a newly constructed intake pipe in the middle of the River.

In 1632, King Charles I granted a charter to Cecil Calvert, Baron of Baltimore, for a new colony north of the “River of Pattowmack … unto the further Bank of said River.”

The southern boundary for the new colony Maryland (named after the wife of Charles 1, Queen Henrietta Maria), extended to the low water mark of the Potomac River on the Virginia shore (i.e., “unto the further Bank of said River”).

After the American Revolution, Maryland objected to Virginians poaching fish from “its” Potomac River. Among those Virginians was George Washington, who found his herring fishery in the Potomac offshore from Mount Vernon to be a more reliable source of income than growing tobacco and wheat.

With George Washington’s assistance, Maryland and Virginia agreed in the Mount Vernon Compact of 1785 that neither state would interfere with the other’s trade or fishing in the Potomac. Despite the express language of the charter, Maryland’s senior representative to Mount Vernon, Samuel Chase, was do doubt aware that with the recent rebellion against the King, the authority of the King’s prior land grants was not clear. But Virginia’s real leverage was its threat to close the Chesapeake Bay to Maryland navigation, blocking ships passing through the mouth of the Bay. Maryland might have controlled the Potomac, but Virginia controlled Cape Charles and Cape Henry.

Of note is that the Maryland Virginia boundary on the Eastern Shore had required negotiations more than a century before the meetings at Mount Vernon. In 1668, a commission agreed to set the boundary along the 38th parallel, where the Potomac empties into the Chesapeake Bay. Unfortunately, the boundary was marked using magnetic compasses, without correcting for the deviation from true north. After the commission marked the boundary, it was realized later that the line was 5 degrees off from a true east west slant, hence the “tilt” in the state boundary evident on maps today.

The two states had a continuing series of boundary disputes and resolutions, including an arbitration in 1877 known as the Black and Jenkins Award that reaffirmed Maryland’s sovereignty over the entire Potomac up to the low water mark on the Virginia shore.

After the Civil War, Maryland and Virginia each supported the claims of their separate watermen to valuable fish and oyster resources by establishing “navies” on the Chesapeake Bay. While the last “shoot outs” between fishermen from the two states apparently took place on 1897, disputes (including which state could enforce oyster dredging rules) continued until modern times and the adoption of the Maryland-Virginia Compact of 1958, negotiated at Mount Vernon, again.

The current dispute is before the U.S. Supreme Court because the Constitution prescribes the high court has original jurisdiction in disputes between the states. Virginia first sought permission from Maryland in 1996 to construct an intake pipe to serve the drinking water needs of Fairfax County. After initially denying the request, Maryland did eventually issue a permit, but imposed conditions to which Virginia objects.

In speculating how the high court might rule, many attorneys are heard to argue the law is clear, dating back to the 1632 charter, and Maryland owns the Potomac including the waters of the Potomac. But historians point to Virginia’s record of successes in over 350 years of disputes and challenge the basis of Maryland’s denial of the permit on inappropriate 21st century anti-sprawl considerations.

The best indicator of how the Virginia’s claim may be adjudicated by the Supreme Court is the finding of Ralph I. Lancaster, Jr., a special master appointed by the justices, who recommended that “Virginia and its citizens have the right, free of regulation by Maryland, to construct in the Potomac appurtenant to the Virginia shore and to withdraw water from the Potomac.”