The oil company calls it “seepage.” Environmentalists describe it as a “blow out.”

Either way, the leak at the oil sands project in Northern Alberta — which has spilled 280,022 gallons of oil across 51 acres since June — is stoking the controversy over the energy source.

“This mess is a symptom of the problems with the reckless expansion of the tar sands,” said Anthony Swift, a lawyer in the international programs division of the Natural Resources Defense Council in Washington. “Environmental regulations have just not caught up.”

The oil sands industry is booming in Canada, pumping billions of dollars into the economy and providing thousands of jobs. But critics contend that the processes for recovering the low-grade petroleum called bitumen are particularly harmful to the environment. President Obama is weighing climate concerns in his decision to approve — or not approve — the Keystone XL pipeline, which would link Canada’s oil sands with the American Gulf Coast.

The cause of the oil spill at the Royal Canadian Air Force base in Cold Lake, Alberta, remains unclear. The company that owns the project, Canadian Natural Resources, blames abandoned wells in the area. Environmentalists point to fundamental flaws with the company’s process.