Mayo RCMP Const. Michael Potvin, 26, was last seen on July 13 swimming for shore after his boat capsized in the Stewart River. (RCMP)

Missing Mayo RCMP Const. Michael Potvin is presumed to have drowned, says the force's chief in Yukon.

Potvin, 26, wound up in the Stewart River at Mayo on July 13 when the boat he was in capsized. Witnesses said he swam for shore and was only a few metres from the riverbank when he went under.

Despite extensive search and rescue efforts, Potvin has not been found and the passage of time and the swift river currents eliminate the likelihood that he will be found alive, Chief Superintendent Peter Clark, Commanding Officer for Yukon RCMP, said in a statement Tuesday.

"Any time a member of the policing community loses their life while performing their duties, it impacts each of us," Clark said. "The loss of Mike is tragic and this has been a most difficult time for everyone concerned."

Clark said Potvin and his wife, Allison, who is seven months pregnant, were assets to the area they lived in.

"My understanding is his wife and himself moved about the community and they were extremely active and very well liked. By all accounts, they were very much appreciated and by the level of community support that I saw personally … he's a huge loss."

The Potvin family is holding a memorial service in Ottawa, where Michael Potvin grew up, on Aug. 4. It will take place at Saint Patrick's Basilica, 281 Nepean St., beginning at 9:30 a.m.

A memorial service in Yukon is also being considered, said Clark.