California is very unlikely to appropriate water from the Great Lakes. It would be too costly and, you are correct, there are better alternatives. What is more likely is that the large California Congressional delegation will sympathize with other states suffering from drought. If the Great Lakes watershed is considered mismanaged at the time, the compact will be vulnerable. That is why it is imperative that the Great Lakes states and provinces manage the watershed even better. Note, I make this argument in an effort to put a fire under the Great Lakes region to improve management of the lakes. I’m originally from the Great Lakes watershed and would hate to see it diverted.

I presume huge amounts of water are used for irrigation. Perhaps the time has come to use advanced techniques such as “drip” irrigation which have been extensively developed in arid climates.

Nuclear powered deslination plants along the coast are another technically feasable way of providing large amounts of fresh water for Californian population centers.

But I think that many people will object to having pipelines built only to water lawns and fairways for housing tracts and golf courses in Arizona and Nevada.

California has a lot to do to clean up its own water management act before appropriating more water from elsewhere.

http://en.wikipedia.org/wiki/California_Water_Wars