Lake Mead agreement: A promising precedent on water rights:

The total amount of water involved in the five-year “trial run” agreement signed last Tuesday between Mexico and various southwestern states and water agencies – amending a 68-year-old treaty on rights to water in the Colorado River – is not inconsequential. But the real breakthrough may lie in the precedent it sets.

In exchange for a $2.5 million investment in infrastructure south of the border, the Southern Nevada Water Authority will receive a one-time share of 23,700 acre-feet from the savings Mexico expects to see from lining irrigation canals and upgrading irrigation methods. (One acre-foot is enough water to supply two average Las Vegas homes for a year.)

The two largest municipal water agencies in Arizona and California – the Central Arizona Water Conservation District and the Metropolitan Water District of Southern California – have reached similar deals to help fund efficiency improvements in Mexico and share in the resulting water savings.

This may not be “buying water,” by the most rigorous definition. After all, the 1944 treaty which grants Mexico 1.5 million acre-feet of river water each year – enough to supply about 3 million homes – makes it the lifeblood of Tijuana and other cities in northwest Mexico, where talk of selling part of that share back to the northerners can be fighting words.

But whether Mexican needs are protected through canal improvements or eventual construction of desalination plants, the precedent is still there. This is the beginning of a creation of something more like a real “market” in water, which is the best long-term solution for the entire region.

So long as we’re talking voluntary sales and not state coercion – so long as farmers are free to negotiate their own price – if urban populations can afford to pay more for water than melon ranchers, then that’s how the market tells us the best way to allocate that resource.

Last Tuesday’s California signing ceremony capped five years of often frustrating bilingual negotiations.

The far-reaching agreement signed near San Diego gives Mexico badly needed storage capacity by granting it rights to leave some of its river water in Lake Mead.

In exchange, Mexico will surrender some of its allotment when the water level in Lake Mead drops to 1,075 feet, and reap some of the surplus when it rises to 1,145 feet, bringing itself in line with western U.S. states that already have agreed how much they give up in dry years.

Under the pact, Mexico could leave as much as 1.5 million acre-feet of water in Lake Mead over five years.

That’s enough water to raise the lake’s surface by as much as 15 feet and offer some protection for the intake pipes through which the Las Vegas Valley draws 90 percent of its drinking water.

The Southern Nevada Water Authority’s $2.5 million would be paid to Mexico over three years starting in 2014. The authority would have until 2036 to draw on the 23,700 acre-feet.