An outbreak has been announced at the NWT Power Corp (NTPC) Snare Hydro System worksite.
This comes after two workers have developed COVID-19 since Sept 11, including one individual who got the virus on site.
Public health officials say they are working with NTPC to ensure the infected individuals safely isolate.
There is one other active case each at Diavik and Gahcho Kue mine.
All known cases in closed NWT worksites for the month of September involved out of territory workers.
The total active case count in the territory is 199 with 128 coming from Yellowknife.