A treasure trove of untapped northern resources could be up for grabs later this year when a temporary ban on development in one of Canada's most rugged and beautiful national reserves expires, an environmental group says.

The United Nations designated the Nahanni as a world heritage site in 1978. (CBC)

The Canadian Parks and Wilderness Society warns industry could descend on the Nahanni National Park Reserve and stake claims when the interim ban ends in October unless the federal government permanently grants the reserve protected status.

"There's certainly concern that without the final boundaries drawn and protected, staking could resume," said society spokeswoman Ellen Adelberg.

Environment Minister John Baird said he's confident the government will finish the process to permanently protect the Nahanni before the interim development ban expires. He cites lengthy consultations and assessments as reasons for the delay.

"We've established all these processes to stop bad things from happening to the environment, and when you want something good to happen, you still have to go through all these processes, which can be time-consuming and can be frustrating," he said.

"But we're committed to a massive expansion of the Nahanni National Park."

Then-prime minister Pierre Trudeau originally set aside the Nahanni in 1972 to protect it from proposed hydro-electric development after he was struck by the area's rugged beauty. The park's mighty river winds through craggy canyons, plunging in thunderous plumes at mammoth waterfalls along the way. Wolves, grizzly bears, lynx and woodland caribou roam the dense boreal forest.

The United Nations designated the area a world heritage site in 1978.

Nahanni National Park is located in the Northwest Territories. (CBC)

At first, 5,000 square kilometres were protected. Over the years, Ottawa has granted protected status to a swath of land surrounding the park.

The first expansion came in 2003, when an additional 23,000 square kilometres in the area was given temporary protection.

The reserve's boundaries grew again last summer when Prime Minister Stephen Harper announced another 5,400 square kilometres of land would be barred from further development. All told, the park and reserve together now encompass an area that's nearly five times the size of Prince Edward Island.

But the expansion has created a confusing patchwork in which the park is permanently off-limits to development while the reserve around it is only temporarily protected.

The development ban on the reserve's temporarily protected parts expires on Oct. 31.

The region has been eyed with growing interest by diamond, uranium, and oil-and-gas developers.

"There's always interest in the Northwest Territories in exploration of various kinds. It's long been recognized as an area that's rich with resources," Adelberg said.

"And as world demand for so many resources is on the increase, and technology has allowed industry to access areas that used to be too remote for development, that's continually a pressure."

Environmentalists have long wanted the entire South Nahanni Watershed — as many as 38,000 square kilometres — to be protected. Such an expansion would likely include the site of a zinc mine with an ore body valued at an estimated $2.5 billion.

Along with the Nahanni, the society singled out two other national parks in the Northwest Territories — the newly created Naats'ihch'oh National Park Reserve, and the Thaydene Nene National Park — as needing permanent protection.

There are also two marine conservation areas in British Columbia and Ontario, and a handful of provincial parks scattered across the country, in need of greater protection, the society says.