(CNN) -- The first shock in new eco-documentary "Dirty Oil" comes in the first few seconds when a question is asked: where does most of the U.S.'s oil come from?
The answer according to the filmmakers is Canada. For the last seven years America's northern neighbor has been its number one supplier of oil.
Over one million barrels of crude flow down vast arterial pipelines every day to refineries around the Great Lakes and mid-west, where they are turned into the fuel pumped at gas stations.
The majority of this oil is being removed from the "oil sands" of Alberta, in what has become one of the largest industrial developments in the world. "Dirty Oil" argues that the cost of this huge expansion is the health of the land and local people, as well as a huge release of greenhouse gases.
The film contends that an area of virgin forest the size of Florida will be industrialized to extract oil from some of the largest open cast mines in the world, with the whole operation producing three times the carbon emissions of conventional oil extraction.
This is because removing the oil from the oil sands requires huge amounts of heat, which is supplied by burning natural gas and other fossil fuels that emit CO2 and other gasses.
Until recently this intensive process was too expensive. But rising oil prices have turbo-charged the industry, and as the world's energy companies set up offices in this remote area of Canada, big money comes with them.
The town at the center of this black gold rush, Fort McMurray, has more than doubled in size from 40,000 to 80,000 people in the last decade. Thousands of workers are drawn by the promise of very high wages -- one truck driver interviewed in the film says he earns $100,000 per year.
"It was kind of surreal up there," the film's director Leslie Iwerks told CNN. "Fort McMurray is kind of like an old-style boom town."
When making the film Iwerks saw first-hand how the environment has been drastically changed by the rapid expansion of the oil business.
"You drive up Highway 63 [towards the oil plants] and you start to see the slow evolution of forest into these big tailings ponds, and these toxic lakes are everywhere," she says. "You can smell it; my lungs would ache by the end of the day."
The oil sands are truly an industrial landscape operating on a dizzying scale, and the film shows how the mines stretch from horizon to horizon, as trees are felled and the entire forest floor is dug up and processed.
"At times, it was weird, I had some off-record conversations with oil workers, and they were kind of aggressive," says Iwerks.
"They had seen filmmakers come in and tear it all down, and they were very defensive.
"But at the same time I could see there was a conflict -- I remember one guy told me: 'If you're serious about doing this I have some really horrific stories about people and animals, things that have never been reported'. I kept saying 'can you tell me?' And he just said: 'I just can't; if I do I'll be gone.' He had this real moral dilemma. I could feel it."
The film lines up ranks of local First Nations people, doctors, ecologists and others who all assert that the health of people and animals is being adversely affected by the oil works. Dead birds washing up in the tailings ponds, mutant fish in the rivers and lakes, and a boom in local cancers are just some of what they claim are many visible signs of this degradation.
But representatives of the Alberta government and the oil industry firmly reject most of these claims, saying the business is as clean as it could be, and operating to standards way above those expected elsewhere in the world. Even the scale of the industrialization seems open to debate, especially the claim that an area the size of Florida is up for development.
"That's absolutely false," says Mel Knight, Minister of Energy, Alberta, in the film. "The maximum amount of Alberta that could be developed is around 20 percent; 80 percent of that would be reclaimed in situ, the same as where oil is recovered in Texas or California or anywhere else in North America, for that matter... We're not ripping and tearing up most of Alberta, and indeed I think our reclamation standards are above what most mining operations are prepared to do... They have to reclaim every square inch."
As a filmmaker one of Iwerk's biggest challenges was staying objective.
"But at the same time you have to stay true to your instincts... I can honestly say as a human being on this planet I'm concerned -- what is probably the largest energy projects on the planet has to be doing some damage. It can't be all roses," she said. But, according to Iwerks, the answer isn't just to leave the oil in the ground and walk away, despite the problems.
"That would be naive; if there's a resource in the ground people are going to exploit it," she says.
"They're not just going to leave it there, are they? This is a multi-billion dollar industry and there's a need for oil. But there's also a need for balance between industry and the environment. The Alberta government should be putting tons of money into finding the cleanest way of doing this."
Ultimately, it's the potential of green technology that gives Iwerks hope.
"I think that we can tell this story, and say that it's all woe. But ultimately we have to ask what can we do about all this? It's so easy and habitual to go to our car and pump gas every day, but until we can start to think smarter, until we think about the potential of wind, solar, hydro, we won't move forward.
"If people take one thing from the film, I'd like them to be moved in a way that will inspire them to live a cleaner, greener life."