Virginia is entitled to take water from the Potomac and to build pipes, piers and docks into the river without Maryland's permission, a U.S. Supreme Court special master wrote in an opinion released yesterday, invoking charters from 17th-century British kings and a compact between two of the states' most revered statesmen.

The 97-page report by Ralph I. Lancaster Jr. marks a significant victory for Virginia and the beginning of the final chapter in a state-vs.-state battle over use of the river that has sparked skirmishes for nearly 300 years.

The court case at hand began six years ago with a dispute over a Fairfax County proposal to build a new water intake pipe -- a dispute that came to symbolize a broader debate over the balance between environmental protection and development. But attorneys arguing the case reached far back in history to make their points, citing a 1632 charter from Britain's King Charles I that granted the river "from shore to shore" to Maryland; other royal charters; a 1785 compact reached at Mount Vernon by Samuel Chase, acting for Maryland, and George Mason, for Virginia, among others; and the writings of George Washington, James Madison and Thomas Jefferson.

Lancaster, a Maine lawyer appointed by the high court to referee the case, issued his report after two years of consideration and a failed, last-ditch effort at mediation. He ultimately sided with Virginia's interpretation, relying, in part, on a 1910 Supreme Court decision in a similar dispute between Maryland and West Virginia that used the same historical references.

"I recommend that the Court enter judgment declaring that Virginia and its citizens have the right, free of regulation by Maryland, to construct improvements in the Potomac appurtenant to the Virginia shore and to withdraw water from the Potomac," Lancaster wrote. He declined to comment on his findings because the case is pending.

The high court has not said when it will consider Lancaster's report or whether it will hear arguments. Both sides can file comments, and the justices can accept, reject or modify the recommendation. Most often in disputes between states, the court accepts most of the special master's report. In July 2001, Lancaster issued two reports to the states; yesterday's report was the first in which he has made a recommendation to the Supreme Court.

Maryland officials, who announced that they will file exceptions, said the state's regulatory process is necessary to protect the river as a natural resource.

"Maryland has a responsibility, as owner of the Potomac for nearly 400 years, in caring for this important natural resource to the fullest extent possible," Maryland Attorney General J. Joseph Curran Jr. (D) said in a statement.

Virginia Attorney General Jerry W. Kilgore (R) praised the recommendation as an "important victory for economic development and quality of life in Northern Virginia." "Ensuring that Virginians have access to water in an environmentally sound way will help ensure that Northern Virginia remains strong and vibrant," he said.

The case has its roots in a 1996 decision by the Fairfax County Water Authority to replace an intake pipe near the Loudoun County border. Fairfax officials sought to replace the existing pipe with a longer one because water near the shore had become increasingly muddy. Maryland turned down the request for a permit. An administrative law judge and then an environmental official ruled in favor of Fairfax, but Maryland officials appealed.

In February 2000, Virginia sued Maryland in the U.S. Supreme Court. The pipe eventually was built, but Virginia has asked the court to rule that Maryland cannot require permits for other water pipes and similar projects.

At its core, the legal battle is a border dispute. Most boundary rivers are split down the middle. But the 1632 grant from Charles I gave Maryland sole ownership of the Potomac. Arbitration in 1877, which was later ratified by both states, designated the low-water mark on the Virginia shore as the boundary.

A 1785 compact gave each state the right to fish on the river and to make improvements as long as they didn't obstruct navigation.

Maryland Solicitor General Andrew Baida, who declined to comment yesterday, has argued that Maryland has required local governments in Virginia to seek permits for water intake pipes and should be allowed to continue that practice. Maryland officials argue that even if Virginia did have the right to the water without Maryland's approval, it lost that right because some Virginia localities have abided by Maryland's permitting process.

Stuart Raphael, special counsel for Virginia, said the commonwealth has the right to take water from the river without permission. "The compact gave Virginia the right of access. It was implicit that Maryland did not have the right to regulate that access," Raphael said yesterday.