A federal judge here ordered the U.S. government yesterday to pay $5,000 in damages to a Washington peace activist who was imprisoned an additional 15 days in 1975 by an apparent clerical error.

The amount was awarded to Mitch Snyder, a member of the Community for Creative Nonviolence at 1345 Euclid St. NW, by U.S. Senior District Judge Edward M. Curran after a three-hour trial.

Snyder said lat night in a telephone interview that the award would not be used by him personally, but that "our community would decide" the manner in which the money would be spent.

Snyder was sentenced to 90 days in jail after he was convicted in connection with a blood-throwing incident at the Vietnam Overseas Procurement Office here in 1974.

On May 15, 1975, while Snyder was serving his jail term, U.S. District Judge John H. Pratt, who had sentenced Snyder originally, reduced the term to 60 days effective May 20. The U.S. Marshal's Service was supposed to transfer the order to the D.C. jail to arrange with the D.C. Corrections Department for the release.

Snyder did not actually get out of jail until June 4, after his attorney had routinely consulted with the judge's office to find the status of the case.

There was no conclusive proof as to what had delayed the release, but Curran found that evidence indicated the marshal's service had been "negligent" in not getting the order to the jail on time.

Snyder contended that he had suffered unnecessary physical trauma during the extra 15 days in jail. He also has a suit pending in D.C. Superior Court concerning the medical conditions at the jail, where he received minor surgical treatment.