The Economist.com reported that trading water would help alleviate water shortages.   With water consumption doubling every 20 years, according to Goldman Sachs, lack of water could prove to be a bigger threat to mankind than rising food prices or the depletion of energy resources. 

Goldman expects profits to be "made less from selling the stuff directly, and more from investments in infrastructure and new technology. The bank estimates that America alone needs to spend around $1 trillion on new pipes and waste-water plants by 2020. It estimates that the higher-tech side of the industry—for example in desalination efforts, or ultraviolet disinfection—is now worth $425 billion dollars, globally."

There will also be plenty of money made in supplying water and owning water rights.  More efficient water markets would be one way to share out water with out as much waste.  

PICO Holding, Inc (PICO) is a diversified holding company whose whose major activities include owning and developing water rights and water storage operations in the United States.