A federal judge will hold an emergency hearing Aug. 13 at which she will consider imposing an inmate population ceiling at Lorton Reformatory's Occoquan I, II and III facilities and instituting a special inmate release program if overcrowding persists.

U.S. District Judge June L. Green ordered the city yesterday to provide information within seven days on the capacities of the three facilities -- the site of a fiery uprising two weeks ago -- and the number of inmates that might be freed if their minimum sentences were reduced by 30, 60 or 90 days.

Green indicated that she might issue a ruling at the hearing, raising the possibility that the city's continuing prison crisis could deepen dramatically.

Assistant Corporation Counsel Michael Zielinski objected to Green's plans to hold the hearing, arguing that it would be improper for her to impose an inmate population limit without a thorough investigation of the facilities' conditions and a hearing on the results. He said the city would have provided any information the court wanted without an order and that some data was turned over yesterday.

The Occoquan complex, which before the July 10 uprising held more than 1,750 persons, or about 25 percent more than its capacity, has served as the city's major relief valve for meeting court-imposed inmate caps at five of its nine prisons. Imposition of a population limit at Occoquan would leave the city no place to house additional prisoners.

The proposed phased-release program, which would not include inmates serving life or mandatory minimum sentences, is similar to proposed legislation that has been pending before the D.C. Council for more than a year. The bill, which has been backed by Mayor Marion Barry as part of the agreement that resulted in the imposition last year of a 1,694 inmate population ceiling at the D.C. Jail, is opposed by U.S. Attorney Joseph E. diGenova.

Peter J. Nickles and Alan A. Pemberton, attorneys for inmates at Lorton's Central and Maximum facilities, made the request for an inmate population ceiling and a phased release program. Nickles argued that continued overcrowding throughout the prison system jeopardizes the city's ability to comply with court-ordered limits and complete mandated renovations at Central and Maximum.

Zielinski vowed that the city would meet both the inmate population ceilings and the scheduled renovation, but he questioned whether the attorneys for Maximum and Central inmates should be requesting inmate population ceilings at Occoquan.

The crowding at Occoquan would have a "very limited effect" on the Central and Maximum inmates, Zielinski said, and he urged the judge to "remember where you are" legally. Zielinski also pointed out that the American Civil Liberties Union's National Prison Project has been making inspections at the Occoquan facilities that could lead to a lawsuit on behalf of inmates there.

Steven Ney of the National Prison Project said in an interview after the hearing that his group welcomes the move by Nickles to address what he called a "system-wide problem that the District has failed to address."