Looks like this in the GECK:
http://i.imgur.com/l4K98.jpg

Looks like that, except as if the river was dried up, surface of water is invisible, but you still get splashes if you shoot it, and can still swim, there's just zero indicator that there's water there otherwise.

It's in a new worldspace, if that makes a difference.

I did http://www.youtube.com/view_play_list?p=6CA8C36158924E10 a while back for FO3 that might help. It's usually the water type/noise texture that is missing/incorrect which causes the water to be "flat" and or invisible.

You need to set it up with a reflection/refraction.

Put a fungus or something at the bottom of the water and then set the fungus to be in the refraction list of the water. That should make it show up in game.

Done it !

Simply two keys :

- Do the water level high enough ; I've put 13000 like I was doing for Fallout3, and 11000 for land level. it can be lower I think, but gotta try.
- Put the watertype potomac and waternoise texture that fits with it ( wastelandwaterpotomac). If you want other types of water, make copy from potomac type, and modify your new one to be as you want.

http://img253.imageshack.us/i/falloutnvworldspacetry0.jpg/