Requiring time to deliberate, Justice Virginia Schuler reserved her decision following Monday's proceeding.

The NWT Land and Water Board ruled that an environmental assessment must be conducted before a water licence is renewed for CanTung mine.

North American Tungsten Ltd. is challenging the board's order, which would involve ecological, social, economic and cultural analysis of the mine.

The mining company's position is that it's water licence was renewed several times prior to the Mackenzie Valley Resource Management Act coming into effect.

It wants a "grandfather" clause to allow it to retain the existing stipulations for a licence.

CanTung mine, which is 40 kilometres from Nahanni National Park Reserve, went back into production in January after 16 years of dormancy.

Calls to the CanTung mine site and to North American Tungsten's head office in Vancouver were referred to president Udo von Doehren. He was en route to the mine site Tuesday and couldn't be reached for comment before deadline.

Environmental groups have aligned with the Land and Water Board.

This is the first court challenge of the board's order for an environmental assessment, making Schuler's decision precedent-setting in the NWT.