A few more details are coming in. Nobody was searching for them in Nevada (their ultimate destination), as the last place they were seen was in Oregon.

http://www.cbc.ca/news/canada/story/2011/05/06/penticton-couple-woman-found.html

"Police said she told them they became stuck on the logging road March 21 and she had been there since then, surviving on water alone."

http://www.cbc.ca/news/canada/story/2011/05/06/penticton-couple-woman-found.html

"On Saturday, teams began searching in Nevada's Elko and Owyhee counties. The Chretiens' van was found near the Nevada portion of the Bruneau River and the town of Rowland.
Officials said weather over the past month in that area has included snow, rain and chilly temperatures, and a road near the Bruneau River saw a large landslide in early April."

Also, there are hints that GPS may have been a factor. Apparently they had a car GPS, which the husband took with him when he went for help. Some commenters on the news stories indicate GPS in the area directed them to turn onto this logging road, but they ignored its 'advice.'