It’s a strange notion, the cutting off of water across an invisible territorial boundary. There are few actions we can take as humans – both for communities and for the environment – that are more baldly assertive than diverting rivers and water flow.

Photo: Ejido Johnson/NWF

The Colorado River delta sits at the very end of the 2330 km-long (1450 m.) Colorado River, which winds southward from Colorado to the Sea of Cortez in Mexico. An object of human geo-engineering for hundreds of years, it’s only in the last century that the Colorado River became one of the most controlled, divided and litigated rivers in the world.

Over the past fifty years, so much water has been used in the United States that the river hasn’t reached the delta or the Sea of Cortez at all, turning what was once a lush system of lakes and marshes into a parched desert.

Collage of historical descriptions of the delta and an image of the dry delta of recent years. “The river enters the sea by a mouth four leagues wide…The Rio Colorado bathes (the land) like the Nile bathes Egypt, giving it great fertility.”
Source: Jordan Wirfs-Brock/Univ. of Colorado Boulder

But this week, for the first time in five decades and timed to coincide with World Water Day, water from the Colorado River flowed at more than a trickle on the southern side of the border in Mexico.

In 2012, the 1944 U.S.-Mexico treaty on river use was amended with an addition known as Minute 319, which aims to support reclamation of the delta through controlled ‘pulse flows’, large surges of water that then trickle off in an imitation of the pre-dam, pre-diversion river that flowed heavily with the snow melt in spring and tapered off through later months.

The surges created by this pilot project should help spread tree and plant seeds across the delta, while the tapering off should provide irrigation for plants to thrive. It’s hoped the influx of water and the re-establishment of plant life will also support the delta’s dwindling wildlife, including many species of migratory birds.

It’s an unusual cross-border project in that the water release isn’t specifically for commercial purposes, but to support environmental restoration.

Cross-border water cooperation and sharing to support ecosystem recovery: I suppose these days, that’s a strange notion, as well.

Colorado River Dry Delta, terminus of the Colorado River in the Sonoran Desert of Baja California and Sonora, Mexico, ending about 5 miles north of the Sea of Cortez (Gulf of California).
Photo: Peter McBride USGS / Wikipedia