I also took swimming lessons at Larsen, but I don't recall them as "enforced". Maybe things had changed by then (early '60's). If I remember correctly, the lessons were provided by the Red Cross and yes, it was still a graduation (Lincoln) requirement to swim the length of the pool.
My Mom never learned to swim and was deathly afraid of the water. Now I have to wonder if this because of this "enforced" swimming lessons... Generally the very most she would ever do whenever she took us to Fleischhacker, Larsen, or Marin Town & Country Club would be to sit on the edge and put her feet in the water. Same was true whenever at the beach; she would only go in far enough to get her feet wet. Once the water hit her ankles she was outta-there. Unfortunately I cannot ever remember going swimming in Sutro's...could be due to this ever-failing memory I seem to have...haha