* Alberta faces growing backlog of abandoned oil and gas wells

As Alberta's energy companies struggle through a prolonged bout of low prices, more and more are walking away from their oil and gas wells, leaving a little-known industry group to clean up the mess.

Alberta's Orphan Well Association is now responsible for 704 wells, up from 164 last year, according to Pat Payne, the association's manager.

"Industry is not doing as well, and it's due to the low commodity prices, low price of oil, low price of gas and declining production," Payne said. "Declining reservoirs [are] catching some of the companies and they're not able to survive."

When a company walks away from a well, it is capped off, but thousands of metres of tubing remain underground and can still transport remaining oil or gas to the surface.

"There is often some level of contamination with these older sites, and the costs really escalate quickly," said Jason Unger of Edmonton's Environmental Law Centre. He wrote a 2013 report arguing for a faster pace in reclaiming abandoned wells. "The longer sites sit abandoned and unreclaimed, there is ongoing risk." he said in an interview.