The proposed Pebble Mine project received yet another blow yesterday when majority owner Northern Dynasty's (NAK) remaining partner, mining behemoth Rio Tinto (RIO) announced it would withdraw from the project and donate its 19% stake to regional charities.

After losing major partner Anglo American in September of last year, the Pebble Mine project has seen its prospects continue to dwindle in 2014. The EPA announced in March, after the release of its final assessment of the potential impact of large scale mining in the Bristol Bay region, that it would undertake a detailed review of the "potential adverse environmental effects of discharges of dredged and fill material associated with mining the Pebble deposit. The review delays the issuance of permits necessary for the project to move forward and may result in the EPA leveraging veto powers its is granted under section 404(c) of the Clean Water Act to permanently block the project.

Despite the controversy surrounding the project and strong local opposition to the flawed Pebble Mine proposal -- which seeks to build the world's largest open pit mine in the midst of the the world's greatest wild salmon stronghold -- the EPA has faced criticism for attending its duty to protect sensitive and valuable environmental areas like Bristol Bay.

Alaskan Governor Sean Parnell criticized the EPA, stating that "it is disheartening to see a company like Rio Tinto take its business elsewhere as a result of the current federal regulatory environment."

In a statement released by her office, Alaskan Senator Lisa Murkowski was quoted as saying, "I understand that many mining companies are reevaluating their project portfolios right now, but I’m concerned by what else may have prompted this decision. If we want to attract investment to our state and our economy, we need a regulatory system at the federal level that is predictable enough to allow responsible development to go forward – at least to the permitting stage, and without the threat of a preemptive veto from the EPA hanging over it."

Individuals and groups that oppose Pebble Mine, however, have greeted the news of Rio Tinto's departure with open arms. CEO of Trout Unlimited, Chris Wood, noted that the departure was "good news for trout and salmon. Good news for the $1.5 billion commercial and recreational fishing industries. Good news for the people of southwest Alaska. The science that Bristol Bay should be protected is clear. The public support for doing so within the Bristol Bay region is overwhelming. It is good to see common sense prevail with Rio Tinto, a major player in the mining world, stepping away from building the wrong mine in the wrong place."

Shares of Northern Dynasty Minerals fell 5% yesterday on the news of Rio Tinto's divestment. Rio Tinto shares rose slightly.