I te 2012 U.S. Olympic Trials i Omaha, Nebraska, te hui tohu a U.S. mo te 2012 Olympics, i uru a Gemmell ki te roopu Orimipia o U.S. mo te wa tuatahi ma te whakaoti tuatahi i te 1,500 mita freestyle me te waa 14:52.19. I te 2012 Summer Olympics i Rānana, i noho ia ki te iwa i roto i nga wera tuatahi o te 1,500 mita freestyle
me te wa o te 14:59.05, a kaore i eke ki roto i nga tokowaru o runga ki te whakamutunga o te huihuinga.