The day was as gray as the Old Executive Office Building. Perhaps it was that. Possibly it was the intermittent light rain, falling on the crowd, that dampened the occasion. Some said it was because there hadn't been enough publicity.

Rarely do the participants in a parade outnumber the spectators, but last Saturday was one of those rare occasions: 8,000 people marched up Constitution Avenue, 1,500 people watched.

Damp, but undaunted, they marched for 2 1/2 hours. Bands and floats filed up the avenue, swept past the review stand where the mayor was seated, and finally, spilled onto the Ellipse where other festivities were soon to be underway.

"Our Children: Our Future," read the sign on a red, white and blue float representing Ward 7. Below the sign, seated on the wooden horses of a mock carousel, were five small girls dressed in blue and white polka-dot dresses. They looked like they were dressed for a fine, sunny day. The sun, playing shy, refused to show its face.

Decked out in blue trousers, gold jackets and tall, silver-specked hats with gold feathers rising from them, members of the Columbians Drum and Bugle Corps marched down the avenue, looking sleek - heavy on the brass and drums.

A Metropolitan police sergeant, asked to estimate the number of spectators, said: "I couldn't give you a fair estimate. If you give them the benefit of the doubt you could say 'a couple thousand spectators and tourists.'

"There wasn't enough publicity," he continued. Many of the people were probably there because they were "coming out of the museums, saw it and stopped."

"Maybe the early rain had an effect on it," said Clarence Turner, the director of the Rabaut Recreation Center and the stage coordinator at the festivities following the parade, which included exhibits, dance performances and music. Nonetheless, he said, "We feel it's a success as an opener of the summer (recreation) programs."

The event, the Mayor's 1978 Recreation Bonanza, was sponsored by a number of organizations, notably the D.C. Department of Recreation, the Mayor's Emergency Task Force and the Metropolitan Police Force.

Marching units, 175 in all, represented the city's 143 recreation centers, the National Guard, each of the city wards, the Red Cross, the Metropolitan Police Department, the D.C. Public Library system and others. The day had been planned to publicize the Recreation Department and its programs.

On the Ellipse, the activities were numberous. Boxing exhibitions were given by the members of the HAM Athletic Club, which operates out of the Elliot Junior High School recreation center in Northeast. Children took pony rides; they watched martial arts performances by the Womble's Kenjutsu Club. They waited in long lines to get into the Jupitor Jump, a large blue and orange, plastic tent with an airmattress floor, where they jumped and tumbled.

Six-year-old Omar Mills stood with his mother by the martial arts exhibition. "What I like best? The people jumping from the airplane," he said. "I liked the people jumping from there - but I'm not going (up) there," he concluded, shaking his head. Was he having a good time? "Ummhumn."

Angela Thompson, and 8-year-old, sat perched on her father's shoulders. What did she like best? She extended her right arm, pointing to the stage in front of her where the Mary Church Terrell Dance Ensemble, part of the Ward 8 recreation department theater group, danced to the 1938 popular song "Flat Foot Floogie." "I like that," she said. Her father, John, "really liked the skydivers."

The skydivers - 11 Army paratroopers diving from belicopters - floated down from the sky with pink, blue, green and yellow smoke trailing from their feet. They twirled and turned, drifting slowly down, as people in the crowd below craned their necks and shielded their eyes from the rays of the sun that never quite managed to break through the haze.