Who is entitled to the water in a river?

South Carolina’s attorney general, Henry McMaster, recently had an article in the
paper concerning the legal battle between South Carolina and North Carolina over the use of water from the rivers which come through N. C. on the way to S.C. He pointed out how the granting of permits by N. C. to certain cities and utilities for the diversion of millions of gallons of water per day could endanger the availablity of water to the citizens of S. C. He called the federal law suit which he had filed a "fight for S. C. rights".

My question is: how can such a conflict be resolved in a way that is fair to all without also coming to grips
 with the whole problem of population growth? On what basis can anyone decide that limits can be put on the withdrawal of the water that is necessary for life? And, even if legislation is passed establishing such limits, how can such legislation be enforced?

Regardless of how these questions are answered, if we do not include a plan to limit population growth, it will be only a temporary solution, if any solution at all.