A uranium mine in Arizona located just 7 miles south of the Grand Canyon national park has begun operations, one of the first in the US to open in eight years.

The opening of the Pinyon Plain mine comes as the US seeks to boost domestic production of the mineral needed for nuclear energy and accelerate divesting from fossil fuels.

But the mine has faced decades of fierce opposition from the Havasupai Tribe, who fear that its operations could contaminate its sole source of drinking water and damage important cultural sites.

“It’s a very, very sad situation – it’s upsetting a lot of tribes in this region,” said Carletta Tilousi, a former Havasupai council member who has been leading the tribe’s opposition to uranium mining in the south-west. “But I think we all knew this was eventually going to happen.”

The Pinyon Plain mine lies within the new Baaj Nwaavjo I’tah Kukveni national monument that Joe Biden designated last year, and is owned and operated by Energy Fuels Inc.

Uranium mining in the region had ceased for years, amid a federal ban on new mining claims around the Grand Canyon. Permitted mines unaffected by the ban sat dormant due to low uranium prices.

But an agreement at Cop28 to triple nuclear energy production as a means to reduce greenhouse gas emissions has boosted demand. Energy Fuels Inc began operations at the Pinyon Plain mine in December and has also begun ramping up production at its Pandora and La Sal mines in Utah, near Moab.

The company cited rising uranium prices in a statement about its activities, as well as “increased buying interest from US nuclear utilities, US and global government policies supporting nuclear energy to address global climate change, and the need to reduce US reliance on Russian and Russian-controlled uranium and nuclear fuel” among their reasons to ramp-up production. The US still buys uranium from Russia, despite sanctions imposed after Russia’s 2022 invasion of Ukraine, but lawmakers have been seeking to divest from the country.

Pinyon Plain is expected to be open for 28 months and produce 1.57m lbs of uranium.

Energy Fuels insists that its operations will not affect aquifers in the region, and points out that state regulators have determined that the mine will not impact local water supplies.

The Arizona department of environmental quality (ADEQ) in 2022 issued an “aquifer protection permit” to the company, after it showed it was using the latest systems to prevent discharge from filtering into groundwater reserves. “There is no science to support the contention that groundwater is at risk,” Curtis Moore, a spokesperson with Energy Fuel, told the Guardian.

Prior to issuing the permit, “ADEQ professionals spent more than one thousand hours conducting a comprehensive review of this extensive technical record” before determining that adverse impacts to groundwater were “extremely unlikely”, a spokesperson for the agency said. The agency reviewed environmental studies, permits, engineering and hydrological reports over 30 years information from the US Geological Survey, to conclude that the rock layers between the mine and the Redwall-Muav aquifer that the Havasupai Tribe relies on are “highly impermeable”.

For the Havasupai Nation, such reassurances are not enough, said Tilousi. In the four corners region of the south-west, the uranium mining in the 20th century littered the Navajo Nation with abandoned mines and tainted aquifers, leaving a generation of Diné workers and their families with lung cancer and other respiratory illness. The Havasupai and other Indigenous communities are weary, she said.

“We’re not willing to risk the livelihood of my community – of 767 tribal members – for the sake of one mining company,” she said. One mishap or misestimation could risk permanently contaminating the sole water source for the tribe, she argued, in a drought-stricken region where water supplies are already limited.

The tribe, as well as local environmental groups, argue that there’s been no extensive study of how groundwater in the region moves and that a plan to undertake long-term study of water impacts first proposed by the Obama administration had stalled.

And, they say, past incidents at the site are cause for concern. In 2016, mine-shaft drilling by Energy Fuel pierced shallow aquifers, causing a surge of contaminated water. In 2017, when the facility’s evaporation pond approached capacity, miners spayed contaminated water into the nearby Kaibab national forest.

“We encountered shallow, isolated aquifers when we drove the shaft, but this was planned and anticipated by us and the regulators,” Moore said, disputing that the 2016 incident was an issue. In 2017, he said the company swiftly responded and adapted systems to prevent such an occurrence in the future.

The mine also abuts two of the tribe’s most sacred sites – Wii’i Gdwiisa and Mat Taav Tiivjunmdva. The tribe’s creation stories centre on those sites, but fall outside their trust land borders, after they were evicted from the Grand Canyon National Park in 1919.

Biden’s national monument declaration last year prevented new mining claims within the borders of Baaj Nwaavjo I’tah Kukveni, but due to the stipulations of an 1872 mining law, mines under development prior to the federal government’s projections were exempted from the ban. The Gold Rush-era law, which still governs mining operations, allowed miners to seize public lands without regard for whether the sites had been home to Indigenous people – and environmental groups are continuing to push for its reform.

“There are so many reasons why this mine doesn’t belong where it is,” said Amber Reimondo, the energy director with the Grand Canyon Trust, an environmental group focused on protecting the region. “And the fact that it is allowed to operate is a stark example of the weaknesses in our regulatory system.”

Across the south-west, local communities and tribes have been pushing back against uranium mining proposals, including in Utah, where the Ute Mountain Ute Tribe is concerned about air pollution from a nearby Energy Fuels mill facility. Similar tensions have arisen around lithium mining in the west, as a need for the metal in clean energy components grows.

“In the rush to move away from fossil fuels, we are neglecting communities and recreating cycles of harm,” Reimondo said. “In order to have a truly just clean energy future, we have to actually work with Indigenous communities.”