The sheriff is going to detonate a block of RDX in the lake on the premise that it'll kill anything alive in the water, including whatever killed Macweeny and the two women at the beginning of the film, and then he and his deputy are just going to drive away without waiting for the killer creature to float to the surface as they were certain was going to happen!? That just doesn't make sense.
Also chomp chomp chomp, looks like three more folks got bogulated I think