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The Grand Canyon is being flooded with 300,000 gallons of water per second in an attempt to save a rare fish from extinction. But the plan to protect the humpback chub is controversial because it involves emptying water from Arizona’s drought-stricken Lake Powell reservoir, created in 1963 when the Glen Canyon Dam was built on the Colorado River.

The dam, which is upstream from the Grand Canyon, provides hydroelectric power to about 650,000 people and has come under strain as more Americans have moved to the southwest for the relatively low taxes and cheap real estate.

To make matters worse, the flow of the Colorado River, which is fed by melting snow from the Rocky Mountains, has fallen to its lowest level in 85 years.

Some locals argue that the dam can barely afford to lose any more water, and therefore tens of millions of dollars of hydroelectric generating capacity, to save a single species of fish.

In other words, the humpback chub is facing a fight to the death with Americans’ need for air-conditioners and plasma TVs. For now, at least, the chub appears to be winning.

At a ceremony on Tuesday Dirk Kempthorne, the US Interior Secretary, pulled a lever that released a torrent of water from Lake Powell into the Grand Canyon through four giant steel tubes.

The water, which resulted in the Colorado River rising by 2-15ft in the canyon, will be switched off after 60 hours. “This gives you a glimpse of what nature has been doing for millions of years, cutting through and creating this magnificent canyon,” said Mr Kempthorne.

Before the Glen Canyon Dam was build in 1963, the Colorado River was warm and muddy, with natural flooding depositing sediment and creating the sandbars that are essential to the survival of the humpback chub, along with that of other plants and fish species. These days, however, the river is cool and clear, with 98 per cent of the sediment carried by the Colorado River now blocked by the dam. It is thought that four species of fish have already disappeared as a result.

The fish aren’t the only ones suffering: even Lake Powell’s recreation industry has been affected, with shrinking beaches destroying half of the camping sites in the canyon over the past ten years. There are now calls to flood the canyon every time there is enough sediment to do so, which could be every year. If this doesn’t happen, say park officials, the sandbars created this week will be eroded.

But Randall Peterson, a regional manager with the Bureau of Reclamation, says that there are no other floods planned for the next five years, meaning that between April and October, the flow of the Colorado River in the canyon will once again become a trickle.

Indeed, the Colorado River is now so heavily used — in particular for irrigation further downstream in the southwest’s agricultural heartland — that it is often completely dry before it reaches its natural end in the Gulf of California.

“This experiment is a charade,” said Nikolai Lash, an official with the Grand Canyon Trust, an environmental group. “It was a glamorous event staged for the media.”

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