HOW DO YOU explain to a high school athlete that he can't participate in a national track meet because the D.C. City Council is at odds politically with, let us say, the state of Georgia? That's the question Stan Mullins, track coach at Washington's H. D. Woodson High School, has been trying to answer recently. Mr. Mullins was to lead a contingent of 42 athletes from the city's public high schools to a prestigious national track meet in Atlanta next weekend. The City Council paid for similar trips in the past two years, and the students performed well on and off the field. Several athletes, Mr. Mullin said, won college scholarships on the strength of their performances in those meets. But this year the council has refused to provide the $2,500 for the group's trip t Atlanta - which means that the students probably won't go. Why? Because the Georgia State Legislature hasn't ratified the Equal Rights Amendment. Get the connection?

That small-minded act perfectly illustrates the foolishness of the so-called ERA boycott resolution the council approved early this year, taking its cue from some national private groups. The resolution, which already has been invoked several times, bars District employees or anyone representing the city from using public funds for travel on official business to states that haven't ratified the ERA. In an effort to show its zeal for the amendment, the council has ignored the difference between private groups, which people join voluntarily, and governments, which are supposed to conduct themselves with the public interest in mind. There is no world of difference between a private organizaion boycotting cities or states because of differing political views and a state or local government body waging economic warfare with public funds against another state government to push its own political views. The City Council has every right to take a position on ERA - for whatever effect that may have on the Georgia legislature. But this exercise in economic warface will not advance the cause of equal opportunity in Georgia. It will merely deny an opportunity to 42 deserving athletes in the District of Columbia.