The school continues downriver. Waxman and Mengers arrive at the water park to intercept Grogan and Maggie, but the piranha attack the resort and kill many vacationers and Waxman. Grogan and Maggie commandeer a speedboat and rush to the shuttered smelting plant at the narrowest point of the river. Remembering the empty facility pond, Grogan theorizes the fish can survive in salt water; if the school passes the delta, they will reach the ocean and spread over the world. He intends to open the smelting refuse tanks, hoping the industrial waste will kill the piranha. They arrive at the plant ahead of the piranha, but the elevated water level has submerged the control office and Grogan must go underwater; he ties a rope around his waist and instructs Maggie to count to 100 before pulling him out. Grogan struggles to move the rusted valve wheel when the school arrives and attacks him. He manages to open the valves just as Maggie pulls him to safety. Maggie takes Grogan back to the water park, where a massive MEDEVAC is tending to the victims; his injuries are severe and he is seen in a catatonic state.