The Lake (1998)

Jackie Ivers is a Los Angeles nurse who returns home to the small town of San Vicente to find that her friends and family have taken on bizarrely different personalities. Jackie notices that everyone who goes into the town's lake come out different. As the movie progresses, Jackie witnesses what is happening to everyone around her as she is kidnapped by people from a parallel world which is the duplicate to Earth but is now polluted and the ozone layer gone. In order to survive, the duplicates intend to take over Earth. The entrance to the duplicate Earth called the vortex, which are located in major bodies of water, ponds, and lakes.