tf2 water problem

anyway i had this funny idea for a screenshot and i needed to do it on arena_watchtower and it had to do with a spy in the water and heavy on inner tube thing but thats besides the point when i loaded it and went to the spot i wanted to use the water was flat white and it tottally ruined the setting is there anyway to fix the water? and make it look like it normally does when you play tf2. its perfectly fine when i play the map on tf2 but its flat white in gmod.