The 57-year-old, who cannot be name by order of the court because his relationship to the victims would also identify them, was sentenced by Justice David Hurley in Newfoundland Supreme Court in Corner Brook Monday morning.
The man had been found guilty in April, following a judge-alone trial. Hurley had heard submissions on sentencing from both the Crown and defence in June.
Crown prosecutor Trina Simms had asked for a prison term of between four and five years, while defence lawyer Mary Boulos had asked for between 30 months to three years of incarceration.
At trial, Hurley heard the girls were between the ages of 12 and 14 when the man inappropriately touched them. The abuse of the biological daughter took place on multiple occasions between 2008-09 and the court was told the incidents were too numerous to quantify.
The court heard of four incidents involving the younger stepdaughter that happened between 2012-13.
In most of the incidents, the man would visit the girls in their bedrooms and touch them. The court heard of at least one incident involving him carrying out brief oral sex.
While the incidents involving the biological daughter were more frequent and more physically intrusive, Hurley gave the man two years for each of the two counts of sexual assault he was found guilty of.
The judge said the abuse constituted a substantial breach of trust that is abhorred by the public and cannot be tolerated.
The man maintained his innocence throughout his trial and has continued to do so since his conviction, so Hurley said there has been no expression of remorse.
In addition to the federal prison term, the man has been ordered to provide authorities with a sample of his DNA and will be placed on the national sex offender registry for the rest of his life.
He is to have no contact with either of his victims while serving the sentence.
He will also be subject to a weapons and ammunition prohibition for 10 years.
Although both the Crown and defence requested a prison term, the man was not taken into custody to start serving his sentence after being convicted in June.
He remained free until Hurley rendered his decision Monday.