The City of Greenbelt has not lost a health spa: It has gained a cultural arts center. At least, that is what the city council decreed when it yielded to center president Konrad Herling's plea to turn the 240-seat Utopia Theater in the heart of Greenbelt from a fitness center to a permanent, comfortable home for local talent in the performing arts.

Since last December, the center's aiam has been to "draw the community closer together," according to its operators. Musical revues, dance, mime, film classics and dramatic works have been produced there, "to encourage Greenbelters back to the theater." In March, a production of Lucille Fletcher's "Night Watch," the center's first live drama, marked the beginning of packed-house community support. (Along with the rising popularity came a doubling of the theater's rent on June 1.)

Events of the sumer season have included coffee houses, a Broadway potpourri, four well-executed one-act plays featuring actors from the center's six-week theater workshop, a baraque concert and a puppet-show.

Hans Christian Andersen's "The Red Shoes," a children's play, will be performed Aug. 8-10 and Aug. 15-17. Bill Manhoff's comedy "The Owl and the Pussycat" is scheduled for three weekends, beginning Sept. 12, to head up the fall season.

When the original theater closed, Greenbelt lost a focal point. Entertainment seekers had to go elsewhere. Supporters of the new Cultural Arts Center feel the trend can be reversed and that the center's presence could help revitalize businesses around it. (The shopping center where it is located will face new competition from the Greenway Shopping Center under construction nearby.)

Those interested in becoming members, making contributions or obtaining ticket information may write to Greenbelt Cultural Arts Center Inc., P.O. Box 439, Greenbelt, Md., 20770, or telephone Paula Lipman at 345-3516 or Konrad Herling at 345-9369. Notes

The second show of the Montgomery College Summer Dinner Theater's season is Rodgers and Hammerstein's "Carousel", continuing Aug. 1-3, with a New England buffet beginning at 6 p.m. For reservations, call 279-5301.

Fans of modern dance should enjoy a performance by the Repertory Modern Dance Company of the Jewish Community Center, "Choreo 18", on Aug. 5. It will begin at 7:30 p.m. in the Commons at Courthouse Square in Rockville. For details on the free performance, call 424-8000, extension 305.

Interesting collages by Johanna Bray will be on display through Aug. 8 at Montgomery College Art Gallery in Rockville. For information, call 279-5155.

Developmental workshops for community performing arts groups will be sponsored by the Arts Division of the Maryland National Capital Park and Planning Commission. Stage management and lighting will be covered in workshops Aug. 2 and 9; management styles will be covered Aug. 23. Call 699-2450 for details.