This may be a stupid question. I am lost. I am trying to get back to the watertower where the boat is from the research facility. How do I get there

where do i find the waterfall

Hope I've got the right part of the game.

Ok, I hope you're at the dock at the moment, or just got past the dock. You should, or should have, fight/fought against an Allosaurus or at least run/ran from it (dunno if it's possible to run past it or if you DO have to kill it).
Anyway, there should be just one available door to go through. Go through it and you should be in the jungle now (Jungle - Passage to North Route).

You'll find another Allosaurus here, so just kill it (or run past it, whichever you prefer). In this area, the should be a small waterfall. Examine it twice to see a leaf suddenly fall down. Follow the leaf until you see Dylan in the distance. You'll find the keycard in a small hole to the left. Follow path to North Route 1.

Now go back to the Water Tower. On your way, you'll see the T-Rex again in Jungle North Route 2. Don't worry though as it doesn't see you.

Fill your weapon and save the game there.

Enter the nearest door to the Marsh and follow the marsh until you exit at South Route 2. Take the left path to get to the Passageway to the Research Facility.

Go to the back of the Research Facility and enter the Control Shack. Refill your weapon here and save the game. Now go back outside and use Dylan's Machete to get rid of the vines on the Research Facility door.

Enter the Research Facility

I hope that helps you a bit. Again, I hope I've started you off at the right place, if not, then I apologise.
Jay