Now, a warmer and drier climate is bearing down on ecosystems that have been deprived of water, fragmented, and otherwise altered, their natural resilience undone by human activities. Stretches have long been depleted, largely because of crop irrigation and the water demands of large cities. The Gila River, which was listed by the advocacy group American Rivers in 2019 as the nation’s most endangered river, drains an enormous watershed of 60,000 square miles. The plop of a bull frog, an invasive species, echoed in the hot, still air.

An egret that had been feeding on the fish flew off.

In one, hundreds of small fish gasped for oxygen. On a recent visit, only a few brown, stagnant pools remained. Water rarely flows there, with an occasional summer downpour delivering an ephemeral trickle. A massive mountain of orange- and dun-colored smelter tailings, left from the days of copper and lead processing and riddled with arsenic, towers where the two rivers meet. The confluence now is a very different place, its richness long diminished.

This lush, wet Arizona landscape, combined with the searing heat of the Sonoran Desert, gave rise to a vast array of insects, fish and wildlife, including apex predators such as Mexican wolves, grizzly bears, jaguars and cougars, which prowled the river corridors. The rivers frequently flooded their banks, a life-giving pulse that created sprawling riverside cienegas, or fertile wetlands braided and beaver-dammed channels meandering oxbows and bosques - riparian habitats with towering cottonwoods, mesquite and willows. The confluence of the tiny San Pedro River and the much larger Gila was once one of the richest locales in one of the most productive river ecosystems in the American Southwest, an incomparable oasis of biodiversity. This story was originally published by YaleEnvironment360 and is reproduced here as part of the Climate Desk collaboration.

Drowning at gila river casino