Why did the dog cross the river?

It’s an answer that only Jasper, the 63-kg (138-pound) Great Pyrenees knows — but his human family is happy to have him back anyway.

Mary and Brent Hummel of Castlegar, B.C., are thanking their lucky stars they were reunited with the big dog, who spent three days in the wild and apparently managed to swim across North America’s most powerful river flowing to the west coast three times.

Jasper somehow got out of the Hummels’ backyard on July 2, appearing to vanish into thin air.

“He’s kind of hard to miss. If there was a dog walking down the street that looks like a polar bear, someone would have seen him. He’d just evaporated,” said Mary.

The couple put out a call on social media, and got a tip that very evening — a boater on the Columbia River who spotted a large white dog.

The sighting, however, was on the other side of the Columbia.

That kicked off a fruitless evening of searching. The next day, however, another tip came in.

This time, Jasper had been spotted at a trailer park in Genelle, about 14 km down-river — and back on the waterway’s west side.