The natural beauty and unique species of the Grand Canyon are "in the crosshairs" because of renewed interest in the region's uranium reserves. That is the warning from critics of the mines, ahead of the release of a government report on Friday on the potential impact of fresh mining.

Mining has been banned within the Grand Canyon national park since President Roosevelt declared it a national monument in 1908. But since 2003, foreign companies have submitted 2,215 claims to prospect on the edge of the canyon.

Ken Salazar, the secretary of the interior, temporarily withdrew 1m acres of land from exploration in 2009 to allow time for an environmental assessment. Salazar must decide by July whether to ban "mineral entry" for two-thirds of the claims for the next 20 years.

Uranium deposits mineralise in 2,000-feet deep "breccia" pipes, a geological feature common to the world-famous golden brown sedimentary rock in the canyon. When left alone, the uranium is not harmful. But once dissolved in water, it can leach into springs and aquifers that then feed into the Colorado river, which ultimately supplies 18 million people in the Los Angeles metropolitan area. The water can remain contaminated for decades after a mine shuts.

Taylor McKinnon, campaigns director of public lands at the Centre for Biological Diversity, said the expansion of mining would threaten the park's delicate ecosystem that ranges from desert scrub in the parched canyon to the Californian condors that wheel above the craggy outcrops.

He said: "The Grand Canyon is an international treasure and known for its breathtaking expanses. Its isolated seeps, springs and caves harbour a remarkable diversity of life, including species found nowhere else on earth. Uranium mining puts those species in the crosshairs."

Mining companies have been drawn to the Grand Canyon area since the 1940s, because of large quantities of high-grade uranium that fuelled the nuclear weapons and nuclear power industries in the US.

But fast-paced nuclear power programmes in countries such as China and Korea are fuelling a new rush for "hard rock", and have sent uranium prices soaring from $7.10 a pound in 2001, to $63.88 a pound in 2011.

Vane Minerals, a UK-based company, has submitted approximately 700 claims. Kristopher Hefton, the company's director and chief operating officer, said: "The deposits are among the highest-grade deposits that you can find in the United States, so they are a good target for exploration and mining."

Denison Mines, based in Canada, already operates one mine in the area with plans to reopen three further mines that were approved in the 1980s without being subject to the environmental review. Denison recently told investors that it will increase production by at least 10 million pounds a year by 2020, some of which will be destined for a new nuclear plant in the United Arab Emirates.

Roger Clark, air and energy director at the Grand Canyon Trust, said the post-gold rush General Mining Act of 1872 allowed the exploitation of public land to provide energy security in other countries and for foreign profit, while providing very little economic benefit to the US economy. He said: "We're not building new nuclear power plants in this country and we haven't for 20 years."

"It's a net loss to the federal government. In these [tough] economic times, when hundreds of thousands of dollars are being spent on this report, the mining companies are getting a service that they're not paying for. It's a rip-off."