It's been widely noted that perhaps the most difficult task we'll face as a result of climate change involves resolving cross-border distributional questions. The Los Angeles Times this weekend offered a peek as to how one such dispute is playing out. As the Southwest dries out, the U.S. is beginning to take steps to conserve Colorado River water. Much of the water currently "wasted" as a result of storm and agricultural runoff makes its way back to the river and crosses into Mexico, augmenting the small Mexican treaty allotment of the river's annual flow. So the plans to line canals and build reservoirs to capture the water and keep it in the U.S. are not pleasing Mexico:

Over time, Mexico came to believe it was entitled to the surplus flows, so when the U.S. announced its intention to capture most of the surplus, a coalition of growers and Mexican officials sued. The U.S. Congress essentially mooted the case by exempting the water capture from all federal laws, including the National Environmental Policy Act, invoked by the plaintiffs.

Outraged Mexican officials accused the U.S. of stealing water from the poor to fuel the growth of fancy suburbs in San Diego and Las Vegas, where much of the water is destined to go.

"The U.S. has contravened its obligations once again so that it can get more water flowing to its swimming pools and flower gardens," said Alberto Szekely, a career ambassador with the Mexican Foreign Service and an expert on cross-border environmental issues.

Of course, the U.S. has a pretty compelling case that it's legally entitled to the water, and Mexico's own water-use practices, as the article notes, are rather wasteful. On the other hand, in practice it still amounts to a rich country taking water from a (relatively) poor country, threatening the livelihood of tens of thousands of people in northern Mexico, where aquifers are drying up and the flow to the Colorado Delta (see satellite photo, courtesy of NASA) is already barely a trickle. It's a pretty thorny issue all around and there's no obvious solution.

--Josh Patashnik