YAKIMA, Wash. - In an unprecedented move, tribal leaders from the Northwest and Canada, including the Yakama Nation, have teamed up with the region's religious communities to call for updates to the Columbia River Treaty.

The treaty, signed in 1964, governs the hydropower and flood control agreements between the U.S. and Canada, and is open to renegotiation. In a letter sent to President Barack Obama and Prime Minister Stephen Harper on Tuesday, the tribal and religious leaders said that a modern treaty would include recognizing the rights of indigenous people and promoting environmental stewardship.

The letter is signed by 14 faith communities, including the Roman Catholic Diocese of Yakima, and seven indigenous leaders representing 27 tribes and first nations.

"It's just one piece of paper, but it's historic to have this many religious and indigenous leaders coming together," said John Osborn, a Spokane physician and coordinator of the Ethics and Columbia River Treaty Project, which sponsored a conference in May.

The letter was the result of that conference, Osborn said. It follows in the tradition of a call to stewardship for the Columbia River Basin written by Roman Catholic Bishops in 2001.

The leaders say now that "considering the Columbia Basin as a Common Good means that the basin constitutes a shared international habitat that is an inclusive and integrated human-ecological system, in which our stewardship responsibilities and our moral and legal obligations to native people are actively upheld."

The treaty paved the way for new dams in the upper Columbia River, which provided enormous hydropower and flood control benefits, but decimated the region's salmon populations and other resources important to tribal communities.

The deal was an injustice to native people in the region, who weren't consulted, said Matt Wynne, chairman of the Upper Columbia United Tribes.

"Religious and indigenous leaders coming together to sign and support this declaration underscores that the future of the Columbia River is not just a political, but a moral issue," Wynne said in a news release.

"It helps keep my spirit strong knowing that our struggle for justice and stewardship of the river carries so much faith-based support."

The letter calls for an updated treaty that will require fish passage at dams, protect ecosystem health and cultural resources, adapt to climate change, and include tribal leaders and local communities in future decision-making.

The call for negotiation is timely as the treaty celebrated its 50th birthday last week, and some key terms, including how much flood control Canada provides the U.S. and how it is compensated for the service, are set to expire in 10 years.

In December, the federal agencies that manage the hydropower system recommended updating the treaty, including protections for the river's ecosystem, and this spring Northwest lawmakers called on Obama to make treaty negotiations a priority, but the administration has yet to initiate talks with Canada.