The sixth annual Perrier Cherry Blossom classic Sunday morning is less a sports event than a cultural happening.

Imagine West Potomac Park as a magnet luring every warmup-suited, Adidas-shod, five-miles-a-day jogger from here to Pittsburgh and beyond. Add the presence of Bill Rodgers, the world's premier marathon runner. Throw in 5,000 bottles of chilled French mineral water donated by the sponsor, Perrier, and you have all the ingredients for a Woodstock on the run.

"Curb-to-curb runners, as far as the eye could see," writes an enthusiastic participant in the current issue of Running Times magazine. "To the horizon in front and in back, to Canada and Mexico, for all I know. More runners than I've ever seen in one place - in when? Surely we need a parade permit, or a war permit, or a card reminding us of our right to peaceful assembly."

This year, race organizers are worried that things may get out of hand: 3,426 entered in the ten-mile race, a thousand more than planned for; plus another thousand or so expected for a two-mile "fun run." Race officials have urgently asked unofficial runners to stay away, except as spectators.

Jeff Darman and Ed Murray, race organizers, in an open letter to runners said: "We appeal to you as runners not to run unofficially and to discourage anyone else who you think plans to do so . . . Everyone can not run at the same place at the same time."

The mob scene on Sunday is the latest manifestation of the running boom nationally and in this area. In the past year runners have turned from a somewhat freakish minority to trend-setters and cultural models. Time and Newsweek published cover stories on running, and The Complete Book of Running by James Fixx reached the top of the best-seller lists. A recent Gallup poll indicated that 11 percent of the nation's adults - more than one American in ten - consider themselves runners or joggers.

The Cherry Blossom Classic has been a barometer of running's growing popularity: It began in 1973 as a family-style gathering of fewer than 200 runners; the 532 women entered this year outnumber the entire field for the 1974 event. If you're curious as to what the running boom is all about, Sunday's an excellent time to find out. It requires rolling out of bed well before the 8:30 a.m. start, but many runners will have been up and driving from distant states long before you.

Don't make the mistake of trying to park in East or West Potomac Parks. These will be closed to all drivers except golfers from 7:45 a.m. on. The best advice is to park downtown and walk, as you would for the Folklife Festival or the 4th of July fireworks.

The race will start and finish on Ohio Drive south of the Lincoln Memorial. However, an excellent viewing-site is the Jefferson Memorial, which affords glimpses of the runners at one, four, seven and nine miles.

The star attraction is Rodgers, a lean 30-year-old with flowing blond hair who is currently regarded as the finest marathon runner in the world. Last fall he won the New York City Marathon for the second consecutive year and captured the prestigious Fukuoka International Marathon in Japan shortly thereafter. His 1975 victory in the Boston Marathon established an American record for the 26.2-mile distance.

Challenging Rodgers will be the strongest field yet assembled for the event, including three former Cherry Blossom winners: Dan Rincon, defending champion; Carl Hatfield, two-time winner and course record-holder; and Jack Mahurin, 1974 winner.

The favorite among women runners is Julie Shea, 18, who has captured the women's title in record time for three years in a row.Her winning time last year set a U.S. women's record for ten miles on the road. Challenging Shea will be her sister, winner of the 10-kilometer Atlanta Mini-Marathon, and Aileen O'Connor, a local CYO runner who holds several national age-group cross-country and track titles.

Following the leaders will be a diverse pack of runners representing 26 states and Canada. Entrants range in age from Victor Grossman, 75, a retired Silver Spring postal worker, to Jennifer Amyx, 8, of Frederick, who ran an Olympic-length marathon at the age of five.

There are five entrants 70 years or older. Favored is Ray Sears, 71, a retired postal worker from Shelbyville, Ind., who set a world indoor two-mile record in 1934 and last summer won the marathon title for his age group at the World Masters Championships in Goteborg, Sweden. Sears can expect battle from Paul Fairbank, also 71, a retired GSA lawyer who earned a measure of fame last year by jogging on a treadmill atop a float during President Carter's inaugural parade.

In support of all this activity the Army is providing computer assistance in registering runners and scoring the ten-mile race.