It varies so much, and changes after big floods etc, I doubt anyone bothers to publish anything. If you are after specific area information, then you might get info from people who fish there, but how many barbel anglers bother to find out the exact depth of their swims???? I have in the past, plumbed out large areas using a castable echo sounder, the information gave a decent indication of likely spots, but having caught big barbel from water between 5 and 18feet+ the only way to find out if fish are in any given area is to fish it in different conditions and times of day, these fish are very catchable in daylight, in the right spot, some fish well in the early morning, some mid day/early afternoon etc ,etc. Get out there and try, be mobile, an hour or so will give an indication in the right place/right time, nothing doing move a decent distance, maybe come back later, do not get stuck into the mind set that these fish are nocturnal, in the right conditions they most certainly are not!!!!!!
