The Navajo Nation has approved emergency legislation meant to strengthen a tribal law that regulates the transportation of radioactive material across the largest Native American reservation in the U.S.

The move is in response to the revival of a uranium mining operation just south of the Grand Canyon that has drawn much criticism from environmentalists and Native American tribes in the region.

Navajo President Buu Nygren signed the legislation Thursday as talks continue among tribal officials and Energy Fuels Inc. to craft an agreement that would address concerns about any potential risks to the public or the environment.

The updated law calls for more advance notification of plans to ship uranium ore from the Pinyon Plain Mine in northern Arizona to a mill in Utah. The payment of transport fees and the filing of emergency preparedness plans also are among the mandates.

The tribe in 2005 banned uranium mining across the sprawling reservation, pointing to the painful legacy of contamination, illness and death that was left behind by the extraction of nearly 30 millions tons of the ore during World War II and the Cold War.

Despite that ban, tribal lawmakers in 2012 stopped short of prohibiting the transportation of uranium across Navajo lands. Instead, they declared the tribe’s general opposition to moving ore across tribal lands and adopted regulations to protect human health and the environment by requiring notification and financial assurance, among other things.

Navajo leaders said it was time to strengthen that law and require earlier notification of shipments by Energy Fuels as the company ramps up operations.

Nygren said notification under the existing law didn’t happen when Energy Fuels shipped its first two loads of ore in July and his efforts to have tribal police intercept the semi-trucks were too late.

“The purpose of this legislation is to provide for the protection, health and safety of the Navajo Nation and its people and our precious resources such as our water,” he said in a letter thanking lawmakers for prioritizing the issue.

Navajo Attorney General Ethel Branch said ongoing talks with the company are aimed at making sure any transport of the ore is done in a responsible way. She also made references to the legacy of uranium mining in the region and said remediation work has yet to be done in many locations.

“That’s part of why the (Navajo) Nation needed to respond so strongly here, to push back and ensure that our community doesn’t continue to get disproportionately burdened with radiation and uranium-based waste and contamination,” she said in a statement.

Energy Fuels said Thursday it is optimistic about reaching an agreement with the Navajo Nation that will clear the way for shipments to resume. The company also said the discussions have been consistent with the provisions of the amended tribal law.

“At the end of the day, we want Navajo leadership and Navajo citizens to be comfortable with modern uranium ore transport and to understand that it poses no risk to human health or the environment,” said Curtis Moore, a company spokesman. “And, we are willing to go above-and-beyond applicable federal and state laws to make that happen.”

The Navajo law does make reference to U.S. regulations that govern the transportation of radioactive materials. In general, those rules call for more precautions when enriched uranium, spent nuclear fuel or highly radioactive waste is involved. Uranium ore falls into a different category.

The semi-trucks that will be carrying ore are outfitted with thick plastic covers that are tight-fitting and water proof to limit dust from escaping or rain from seeping in.

Under the Navajo law, the trucks can be inspected, and shipments during tribal fairs along the designated route would be prohibited.

If a company ignored the rules, the Navajo Nation Environmental Protection Agency could issue an order of compliance along with penalties. The Navajo attorney general could also seek a temporary restraining order or injunction through tribal court if the law were violated.