The border closure order issued by the NWT's top doctor is retroactive and anyone returning to the territory within the last 14 days must self-isolate.
The closure became effective on Saturday at noon. The territory's first positive case of COVID-19 was announced Saturday morning.
NWT residents returning to the territory will be asked by attendants at the borders to undertake self-isolation plans, said chief public health officer Kami Kandola during a press conference on Saturday.
"We'll get their names and addresses. The change in direction now is that everyone self-isolate coming into the NWT. It's a directive not a recommendation," she said.
Returnees must submit self-isolation plans to the Department of Health and Social Services (HSS) which can be sent to protectNWT@gov.nt.ca or by phoning 1-833-378-8297.
Returnees can only isolate in Yellowknife, Hay River, Fort Smith or Inuvik, where the NWT's health care assets are most robust.
Lodging would be provided at no cost said Ivan Russell, manager of emergency services with the Department of Municipal and Community Affairs, who was also at the press conference.
"They will be screened and assessed. If they need isolation lodging it won't be at a cost to them for the duration of the 14 days," said Russell.
"Areas are being cordoned off at the airport," he said. "Highway control points are being set up today. They're also providing communication and providing advisories and signage at the stepping off points so someone doesn't drive all the way from High Level and end up at Enterprise."
NWT residents returning to the territory are exempt from the closure but Russell said non-essential travel out of the NWT is not recommended.
However, residents with essential medical appointments will be permitted to go.
Also exempt from the closure are people working in export/import jobs delivering important goods into the territory, such as long-haul truck drivers.
They would be checked and given direction upon entering the NWT and there is an advisory specific to long-haul drivers on the HSS website on social distancing.
But they wouldn't necessarily have to self-isolate, said Kandola.
"We know they come in, drop off their cargo and go back. It's not in our interest to make them go through mandatory 14 days' isolation if they're spending minimal time (in the territory)."
People working in mining or oil and gas are exempt from the closure as well. Kandola said they undergo separate screenings at the airport.
"We've been working with the (company) medical directors on that and providing them with the testing tools to test and isolate symptomatic workers."
In the case of people returning to their families in the NWT, the returnees must self-isolate but families would not, Kandola explained.
"Let's suppose you're a parent and your student is returning from another part of Canada because the university is closed. We're recommending they go to our website and look at what self-isolation means. The family who is there don't need to self-isolate with that person.
"If the student has symptoms we have to test them. But if they're asymptomatic, the people already in the NWT don't need to to undergo 14 day self-isolation. If we do that we could have one-third of NWT residents staying at home for no reason."