Pebble Unlimited Partnership

Photo: U.S. Environmental Protection Agency

The proposed Pebble Mine project has long been a source of controversy in Alaska. It's faced scrutiny nationally, too, as as each presidential administration has taken its own look at the plan to build an open-pit copper and gold mine at the headwaters of Bristol Bay. 

Yesterday, the Environmental Protection Agency dealt the latest blow to the project.

So, what makes this new twist different from the others?