SHIPROCK, N.M. (AP) – Uranium mining companies are showing signs of renewed interest in the Navajo Nation.

The Farmington Daily Times reports that several companies during the past year have addressed the tribe, begging for permission to once again mine the uranium-rich land that the tribe sits upon.

The history of uranium in the area, however, is proving an obstacle.

“As you can guess, there is opposition. There is a legacy issue. There's no doubt about that,” said Albuquerque's Mat Leuras, vice president of corporate development for Uranium Resources Inc.

In addition, several environmental studies have suggested that elevated levels of uranium in and around the mines caused health problems for the people working in and living around them.

The Navajo Nation sits on more than 70 million tons of naturally occurring uranium, a radioactive ore.

Uranium mining companies maintain that history will not repeat itself, especially since they are using advanced technologies and take more precautions.

The tribe still is reeling from the nearly 30 years that the federal government allowed uranium mining on and around the Navajo Nation. Between the late 1940s and the mid-1980s, about four million tons of uranium were extracted from the Navajo Nation.

At the time, uranium was mined to produce nuclear weapons for World War II and the Cold War.

The ore was removed via conventional underground mining, a practice that allowed uranium to seep into the land and water in the surrounding area.

“The industry's learned its lesson,” Leuras said.

While the companies will not be able to extract the uranium within tribal boundaries, they might be able to get at the uranium deposits near them.

The tribe banned uranium mining on its land in 2005, though federal government has jurisdiction on Navajo Trust Land and in the “checkerboard” of Indian and non-Indian land. The trust land is land generally saved for the tribe, and the checkerboard is intermixed federal, state and tribal ownership.

Many of the companies already have secured mineral rights in the checkerboard area.

Uranium companies such as Uranium Resources Inc., Strathmore Minerals Corp., Rio Grande Resources and Laramide Resources Ltd. all have investments around the reservation boundaries. In some instances, however, the companies do need access on the Navajo Nation just to get to their projects.

The Churchrock, Crownpoint and Mt. Taylor area all have such activity.

Most of the companies are using a process in which they use injection wells and extraction wells to circulate water through an underground body of ore. The water does not contain any chemicals but removes the uranium and leaves the rock undisturbed, according to the website for Uranium Resources, Inc., which uses the process for its projects in New Mexico.

The process is supposedly less expensive and safer than conventional mining.

Still, environmental groups have concerns, as do many of the local Navajo communities, though they do not seem overly alarmed by the plans.

“I do not speculate on any deals for renewed mining, because I am focused on addressing the long overdue and enormous workload associated with the remediation or clean up of past uranium mining and processing,” said Stephen Etsitty, executive director of the Navajo Environmental Protection Agency in Window Rock.