Shirley Babashoff has joined the crowd of world-record-class swimmers who, while maybe not washed up, feel washed out before reaching ripe old 21 or 20.

The Californian, who dominated U.S. women's competition for five years only to settle for silver in the Munich and Montreal Olympics, yesterday followed her nemesis, East Germany's Kornelia Ender, into retirement from international competition. Babashoff, who turns 20 at month's end, said she will remain on the swim team at UCLA, where she is a junior majoring in business. But, she said, "I am just tired of swimming. I felt I couldn't do as well as I had done before, and it was depressing."

Still, she has a gold medal from both 1972 and 1976 as a member of the U.S. 400-meter freestyle relay, the memory of 15 times breaking world records (all eclisped now by the Germans) and $5,000 toward her education for five times being most valuable performer at the AAU nationals.

Laughingly, Babashoff offered, "I guess I'm getting old" . . . but there are plenty more where she came from.

For instance, right around here. The Potomac Valley AAU holds the Eddie Rosenbloom Swim Meet this weekend (sessions 7 p.m. Saturday, 7:30 a.m. Sunday) at the Jewish Community Center in Rockville, age groupings from 10-and-under to 15-18, with more than 1,3000 local entrants.