Alligator 2: The Mutation (1991) on Netflix

Plot summary

Beneath Regent Park, a small alligator feeds on discarded experimental animals and chemical waste in the sewers, and it grows to enormous size. When two fishermen die, Detective David Hodges takes the case. A severed leg leads his wife Chris, a university expert, and the coroner to identify an alligator attack. Local tycoon Vincent Brown is planning a party at the lake, and Hodges asks Mayor Anderson to call it off, but the mayor and Chief Speed refuse. Hodges reluctantly takes on rookie officer Rich Harmon, while Brown brings in the hunter Hawkins and his crew to track the creature.