With the opening this week of the 1,757-inmate Eastern Correctional Institution in Somerset County, Maryland prison authorities say the end of years of litigation on inmate crowding is almost in sight.

"There's light at the end of the tunnel," said Emory Plitt, an assistant attorney general and chief lawyer for the state's teeming 13,000-prisoner Division of Correction.

The phasing in of about 50 inmates a week at the Eastern Shore facility from institutions in Baltimore, Jessup and Hagerstown will eliminate or reduce the so-called double-celling and double-bunking of prisoners, free up recreation and storage space now jammed with beds and provide breathing space for Maryland's growing prison population.

The task is a massive logistical undertaking: The physical relocation of more than 1,700 men and their belongings over hundreds of miles of roads in escape-proof buses and vans. Security is tight, plans secret, timing precise. The relocation, to be carried out in weekly stages, will take almost nine months.

And with luck, says Plitt, it also will help close the books on nearly 10 years of litigation in federal court by prisoners claiming that crowding violates their Eighth Amendment right to protection against cruel and unusual punishment.

Like many other states and the District, Maryland has been plagued with prison crowding for more than a decade, a phenomenon caused by rising crime rates and what many prison authorities see as judges' tendency to impose longer sentences and revoke parole more frequently, especially with more repeat offenders.

The crowding has spawned Eighth Amendment lawsuits throughout the country, including two class-action suits filed against Maryland in 1977 and 1978. After numerous hearings, appeals, negotiated agreements and, perhaps most important, construction of the Somerset facility, the crowding issue now appears to be nearing resolution at three of the state's largest prisons in Jessup and Hagerstown, and may do the same at the state's main penitentiary in Baltimore next year.

According to Plitt, transfer of 232 inmates from dormitories and basement areas of the Maryland House of Correction in Jessup and 672 inmates from cell blocks and storage annexes at the Maryland Correctional Institution in Hagerstown will bring both facilities into full compliance with crowding reduction orders by U.S. District Judge Alexander Harvey II.

In addition, Plitt said, the state has agreed, subject to court approval, to transfer 608 inmates from the Maryland Correctional Training Center, also in Hagerstown, reducing double-celling and double-bunking there by about 50 percent. Several other transfers from smaller facilities also are planned, Plitt said, bringing the total to 1,757.

Adjoa Aiyetoro, the national prison project attorney for the American Civil Liberties Union who represents the Maryland inmates, voiced "general satisfaction" with the crowding relief plan.

The state also is under court order to reduce the population of the aging maximum-security penitentiary in Baltimore from 1,250 to 1,103, but it may postpone action until next year. Officials are awaiting completion next July of a "super max" facility adjacent to the Baltimore prison, designed to house the penitentiary's 300 most disruptive prisoners.