We summon like 50 people to the lake to fight the monster via firehoses filled with deadly poison soap. We finally see the monster; it is a fishman with legs. It kills Mr. Garibaldi. RIP.
But, the poison soap knocks it out so we tie it up and put in into a truck for science. It's still alive, so we can study it.
It will probably eat someone else, because unfortunately this movie is not over yet.