Los Angeles, California (CNN) -- James Cameron calls his newest project a "kind of 'Avatar' for real," working alongside tribes in Brazil to save the rain forest.
The Hollywood megamovie director, with war paint on his face and a spear in his hand, met with leaders of 18 indigenous tribes last week to plan their battle to stop a proposed dam that would flood hundreds of miles of the Amazon.
"I sat in what is essentially a war council circle with a number of these leaders and watched them declare to each other that they're going to fight to the last man, to the last drop of blood, and I think they mean it," Cameron told CNN. "I don't think they're just saying it."
Cameron visited Brazil twice in the past month after hearing the tribes' pleas -- prompted after leaders saw "Avatar," his box-office smash about the clash between greed and nature.
"What's happened after 'Avatar' is this explosion of activity around indigenous rights issues, because so many organizations have approached us and said how can we help," Cameron said.
"Avatar" was fictional, but Cameron said he based the ideas in the script on the Brazilian rain forest and the plight of its indigenous people. But he hadn't visited the Amazon region until this year, he said.
"The parallels are fascinating," he said. "You have these people who are essentially a warrior culture."
Cameron's immediate fight is against planning for the Belo Monte dam, which would be one of the largest hydroelectric projects in the world.
"It's kind of the first domino, because there are 60 other major hydroelectric projects in Brazil that are proposed," he said. "If all of them go forward, they'll devastate some enormous amount of rain forest across the entire basin."
Flooding the rain forest would displace 25,000 indigenous people from 18 tribes and another 20,000 nonindigenous residents, Cameron said, but his main worry is the project's impact on the environment.
He said that people usually see hydroelectric plants as green energy sources, but they don't consider the indirect effect caused by the destruction of the trees.
"As these trees become inundated by these upstream reservoirs, they die and they release their carbon that they've been sequestering for hundreds, if not thousands of years," he said. "They release it back into the atmosphere. So we're talking about millions of tons of carbon being released as methane."
Cameron said his role is to bring media attention and political pressure on Brazil's government to stop the dam. "They want this thing to quietly proceed forward and happen without a spotlight on them," he said.
A government auction was set for Tuesday to select contractors for the project.
Cameron has been involved for a decade in promoting green energy alternatives, but he said he also has tried to teach his children about "living responsibly" and "to be citizens of the 21st century with great values."
"We run our household in a very sustainable way," he said. "We generate our own power. We sell it back to a grid. We do organic gardening, composting and recycling."
"Avatar's" website is being updated to help educate movie fans about environmental issues, he said. The release of "Avatar" on Blu-Ray DVD was timed for Thursday, which is Earth Day.
Cameron's company is also sponsoring the planting of a million trees around the world as part of the Earth Day project.