Two miles into Mexico, my hopes of a complete 1,450-mile descent ended in a foamy pond of congealed fertilizers, distillate of countless American lawns and 3.4 million thirsty farm acres.

I splashed out in bare feet, worried that our most iconic white water river would make me physically ill. My companion, Pete McBride, stayed clean by climbing out through the tamarisk trees. We tried to wipe the river shit off our pack rafts with tamarisk fronds, cursing the system that has diminished the Mighty Colorado to a stinking cesspool.

JW on the Colorado River's End, Sonora, Mexico--Pete McBride photo

Then we deflated and taco-folded the little boats onto our packs and began walking the route of 19th-century steamships. Bushwhacking and trudging through sands washed from the Rockies, baked by the hot sun, we perspired faster than we could drink. We stumbled south a dozen miles into Sonora, Mexico.

The sun faded over the distant Sierra del Mayor, dappled an incandescent-carrot hue through steaming Mexicali air pollution, and we collapsed a dozen feet above one of many desiccated water courses. Then we passed the tequila.

The Colorado River has been engineered to death. More than 100 dams and 1,000 miles of canals divert its water to most every farm, industry and city within a 250-mile radius of the river. Each year, seven western states and northern Mexico take 16.5 million acre-feet (enough water to supply 33 million American households) of river water. Amid the 12th year of drought in the southwest, climate models show that conditions will continue to dry the snowmelt-fed river. Add explosive population growth, increasing the demand for water, and the river’s future becomes a ticking time bomb.

This was my sleepless perspective from the 3,000-square mile Colorado River Delta, being subsumed by the Sonoran Desert. Our hips and elbows pockmarked the white sand riverbank. Distant dogs howled with hunger, while the northern horizon burned white hot with the international border’s halogen lights. Since 1998, drought and overuse of the river have stopped it from flowing across this border to the sea. For most of the final 70 miles, Pete and I would be walking.

Dawn blazed straight into the heat of day, and to ease the pressure of water ballasting our packs, we agreed to scrap our ill-conceived rationing plan. Over the next few days, we guzzled 100 pounds of water, shifting the weight from our backs to our bellies, stung by the knowledge that a river was supposed to flow where we staggered through brush and poured sweat and drank water imported from far-off aquifers. Occasionally the river would reemerge in stagnant ponds shaded by cottonwoods and guarded by reluctant great blue herons, icons of a former cornucopia.

We wandered for 10 days, southwest into Baja California, then south toward the Sea of Cortez. Most of the time we were lost in the dried-out maze of delta cut by farm fields, salty canals, potholed tarmac and railroad tracks. Eventually, a small tributary, El Rio Hardy, acted as delta resuscitation – hygienic as an intravenous drip from a catheter. Meanwhile, a newly developed, water-borne infection in my blistered and red swollen feet had me hobbling.

We reinflated our boats and paddled the Rio Hardy before it could be sucked under the vast delta. On the second day afloat, we found an unexpected, wet paradise. The glowing, green-phosphate water turned clear, scrubbed clean by a rowdy coiffure of reeds and plants.

These curlicues of hidden river were lush with an upwelling of underground water, temporarily arisen before it would be reabsorbed and blocked from the ocean by ancient sand grains – spread as far as we could see – carved from and carried 600 miles out of the Grand Canyon. Here, briefly, nature endured: rattling kingfishers, squadrons of circling mallards and hushed, stern-faced cattle egrets. We could smell the postcoital tang of ocean tides.

Tamarisk thinned. Salt grass bearded the ground. Pintail ducks, curlews, ibis, plovers and black-crowned night herons fluttered and gabbled and splashed. We were surrounded by sere mountains and an infinite sky bisected by a once unstoppable river that knew no banks. As the stream narrowed, we could feel it gathering momentum, as if it would once more meet the sea.

I had to stop holding my breath.