The man was sentenced in NWT Supreme Court in Hay River on March 23 after pleading guilty to two counts of sexual assault.
The court banned publication of any information that would identify the victim.
In passing sentence, Deputy-Judge Rene Foisy described the assaults as despicable.
"I have no words in my vocabulary to say how revolted the court is in hearing the circumstances of this case," Foisy said.
Court was told that the assaults began in 1994 and occurred on a regular basis, often two or three times a week.
The man turned himself in to RCMP in Fort Smith in February 2003.
He has been in jail since then. That time was taken into account during sentencing.
The man's lawyer asked the judge to recommend he be allowed to serve his sentence in the NWT.
However, Foisy declined the request, saying there are better programs for rehabilitation of sexual offenders in the federal penitentiary system.