A lot of people say that the Israeli-Palestinian conflict is impossible to understand without a grasp of water politics. I’d say as much about relations between California and Mexico:

To slake the ever-growing thirst of San Diego, 100 miles to the west, the United States has a plan to replace a 23-mile segment of the earthen All-American Canal, which the federal government owns and the Colorado River feeds, with a concrete-lined parallel trough.

The $225 million project would send more water to San Diego, by cutting off billions of leaked gallons — enough for 112,000 households a year — that have helped irrigate Mexican farms since the 1940’s.

But Mexican farmers and their advocates say the lined canal would effectively turn off the spigot for 25,000 people, including 400 farmers whose wells rely on the seepage that has helped turn the powdery fields east of Mexicali, an industrial city, into one of the biggest Mexican producers of onions, alfalfa, asparagus, squash and other crops.

The farmers and their families ask what will they do if they cannot till the fields and answer that they will cross the border, illegally if they have to, in droves.

“They can’t build a fence high enough to stop us,” said Gerónimo Hernández, a Mexicali farmer whose family has worked the fields for generations.

Juan Ignácio Guajardo, a lawyer in Mexicali who is helping a civic group there and two environmental groups in Southern California fight the canal, said, “You can’t have it both ways,” adding, “You can’t take our water away and then say, ‘We don’t want immigration, either.’ “

Full piece here (registration req’d).