LAST WEEK'S Senate ratification of the Panama Canal Treaty marks the welcome completion of an interminably long debate over an issue whose importance has been blown more out of proportion than any in recent memory.

While a defeat would have meant a serious blow to the Carter administration, not to mention a full-scale riot in Panama, the narrow approval of the treaties can in no way be considered a real triumph for President Carter. That the ratification could have been in such jeopardy in the first place does not say much for the administration's much-maligned ability to shape an issue and present it persuasively to the public.

Part of the problem was that the treaty was poorly drafted. The old foreign policy establishment types like Sol Linowitz lost their magic--if they ever had it to begin with. The treaty was highly complex--almost impossible to read--and highly vulnerable to attacks from the Right. A better drafting would have prevented much of the controversy without changing the content.

As it was, Senators like Paul Laxalt (R-Nev.) got a lot of mileage out of it, and even more moderate members--Dennis DeConcinni is the most recent example--raised objections. The result was a little friendly rhetoric to tone down DeConcinni's jingoistic clause about American military intervention. That and a lucky break or two saved the administration from a major foreign policy fiasco.

The U.S. probably did not turn over the canal as completely as it should have but at this point--with ratification behind us--attention should be turned to the far more important issues that have been shunted aside while the country engaged in frivolous debate about an outdated canal.