Terror Basket: Siren's Song (2011)

Louise is star of the university's swimming team, but, after a supposed attack while swimming one day, becomes convinced there is a creature living in the university's waterways that is out to get her. Once it emerges she was taking steroids to aid her swimming ability, no-one believes her story. But Louise, determined she saw what she did, sets out to uncover a sinister conspiracy against her.