Scientists with Environment Canada have found evidence that contaminants from Alberta’s oil sands operations are collecting at the bottom of lakes as far as 100 kilometres away.

The operation's footprint is concerning because it is significantly larger than what was found by a team of researchers at the University of Alberta in 2010. These scientists made headlines when they uncovered landscape contaminated with airborne-heavy metals and other pollutants, 50 kilometres away from oil sands operations.

While the Calgary Herald reported that oil sands proponents have refuted the new findings, senior Environment Canada scientist Derek Muir teamed up with researchers at Queen’s University to take a look at the sediments that had been collecting on the bottom of these nearby lakes.

They found that pollutants called polycyclic aromatic hydrocarbons, or PAHs, increased dramatically beginning in the 1970s, climbing anywhere from 2.5 to 23 times pre-1960 levels.

While Muir says the levels appear to parallel the development of the oil sands industry, with the exception of the lake closest to the oil sands, they were all within guideline limits. Therefore, Muir doesn’t believe the amount of PAHs in these lakes have reached a level that would be toxic to aquatic life.

In a related study, the researchers did, however, find snow closer to the oil sands that contained toxic substances dangerous to fish eggs. According to David Schindler, an aquatic scientist at the University of Alberta who was part of the research team that broke news in 2010, tributaries where young fish hatch in the spring can be largely made up of melt water.

“My big concern is that slowly because of mortalities at spring melt, that this will erode the fishery, killing off the embryos,” Schindler told Postmedia News. He also said this may explain why deformed fish have turned up in Saskatchewan’s Lake Athabasca.

There is a great deal of worry surrounding these findings and more work is underway to sample sediments in other remote lakes in the region.