Enable fog from sccript

I need to enable for if player is below a specific position. Here's the script, but it's not working...

 var position : float;
 var underwater : GUITexture;
 var underwater : Transform;
 var water : Transform;
 
 function Update(){
     position = GameObject.Find("Camera1").transform.position.y;
     
     if(position <= 2001){
         underwater.enabled = true;
         underwater.renderer.enabled = true;
         water.renderer.enabled = false;
         RenderSettings.fog = true;
     } else{
         underwater.enabled = false;
         underwater.renderer.enabled = false;
         water.renderer.enabled = true;
         RenderSettings.fog = false;
     }
 }