Look at what happened in California when they diverted so much of the water to the big cities. Things dried up in a big hurry. It's the ranchers maintaining the reservoirs and water holes out west and making sure that the water stays where it is and the wildlife benefit from that. Back before the ranchers, as you mention, there was a much more even distribution of water because it wasn't being used in such concentrated quantities at certain locations as it is now. The need for beef is what keeps the ranchers on that land and keeps it all from being appropriated and sucked dry. As for the reservoirs and current water supplies, who is going to take care of that if ranchers aren't on public lands? They seal reservoir bottoms to hold water, manage river and stream crossings, maintain roads, and manage the grazing, and pay for the privilege to do so I might add. Do you really want to leave that in the hands of the government? Look at how well they manage everything else. Who is going to pay for that? Do you want to pay a 'water, grazing and road management' tax in every tag you buy? In the short term, a year after removing cattle from the range you might see more elk there. But how many elk will you see in ten years when the water holes have all dried up, in twenty years when thousands of acres have gone up in flames?