A Wall Street Journal article on a recent Phoenix-Tucson water agreement highlights the growing trend among drought-ridden regions of sharing natural resources, and includes insights from sustainability scientists Dave White and David Sampson.

"This is ushering in an era of cooperation where, typically in the past, each player has watched out and protected its own rights," said White, co-director of Decision Center for a Desert City, in the article.

Sampson shared that the Colorado River's flow could eventually fall to as little as 40% of its long-term average.

The agreement the article cites permits Phoenix to send some of its surplus water to Tucson, where it is needed to lower pumping costs. In return, Tucson will give a portion of its Colorado River water to Phoenix when needed.