I have attempted to decompile the map and view it in hammer but i get terrible lag, so hopefully someone will know the texture and say it, thanks
try disabling visgroups n Hammer. You can make it so that it only shows world geometry and hiding entities. In fact you can hide everything EXCEPT water, too. Try again, this time it really shouldn’t lag at all.
You can typically get working (not playable, but working) decompilations by disabling static props in the decompile options.