The Maryland politicians and businessmen eager to resolve a decade-long dispute over the dredging of Baltimore Harbor were given a new weapon today when Gov. Harry Hughes released the results of a study sanctioning a huge proposed dike designed to hold the mud from the harbor's bottom.

The study, conducted by two Johns Hopkins University professors, was begun last summer in response to congressional concerns about the stability of the proposed dike, which would be built on two small islands near the Chesapeake Bay shoreline of eastern Baltimore County.

The rock-and-sand dike has long been the focus of the dredging debate. No politician or businessman in Maryland has disagreed with the benefits of dredging the harbor's main channel to a depth of 50 feet, allowing larger ships with more cargo to dock at Baltimore and bring more money to the state's economy.

But the question of disposing of the resulting 100 million cubic yards of chemical-laden muck has been bitterly divisive. While Hughes, like most Baltimore businessmen, favors walling the mud inside the dike on Hart and Miller Islands, Rep. Clarence D. Long (D-Md.) and his working-class eastern Baltimore County constituents are stridently opposed.

More than a year ago, this antidike group won a federal court ruling requiring congressional approval before the proposed dike could be built on an interstate waterway. Now, while appealing the court ruling, Hughes is strongly wooing the wavering members of Maryland's congressional delegation.

The new report is expected to be a key element in Hughes' battle for congressional hearts and minds.

In their summary of findings, Lucien M. Brush, Jr., a specialist in hydrology, and M. Gordon Wolman, chairman of the geography and environmental engineering department of Johns Hopkins University, conclude that "with some modification of the specifications a dike can be constructed with reasonable safety . . ."

The pair did not recommend that new borings be made on the islands to determine the exact nature of the soil that would form the dike's foundation.

"This [report] will allow us to again pursue the legislative amendment we need (to build the dike)," Hughes aide Hans Mayer said today. "We hope this would get us the support of the delegation."

When Hughes first made his overtures on Capitol Hill last summer, several key congressmen, including Sens. Charles McC. Mathias (R-Md.) and Paul Sarbanes (D-Md.) and Democratic congresswomen Barbara Mikulski and Gladys Spellman, expressed reservations about the stability of the dike, after hearing a presentation by the antidike group.

With Congress on its holiday break and most of Maryland's congressional delegation scattered around the state, it was not immediately clear today whether the report will win over some of the undecided members of the delegation.

Long, seldom known for moderation in his discussions of the Hart and Miller Islands question, today released a statement through an aide saying only that he was "reviewing the report with experts" and would comment "in due time." Members of his staff, however, immediately gave the new study scathing reviews.