A U.S. Supreme Court ruling has put to rest a lingering attempt to derail a Pacific Northwest casino project the Mohegan Tribe has helped develop and will manage for seven years.

In the final event in the saga, the high court indicated Monday that it would not hear an appeal pursued by opponents of the project, a group led by Citizens Against Reservation Shopping, which claimed the federal government erred when it agreed to take 152 acres of land into trust for the Cowlitz Indian Tribe in 2010.

The Cowlitz tribe’s $510 million ilani Casino Resort is nearly ready to open in La Center, Wash., about 30 miles north of Portland, Ore.

“This is a day that both the Mohegan and Cowlitz tribes have anticipated coming for years,” Kevin Brown, the Mohegan tribal chairman, said Tuesday in a statement. “We are very grateful to be able to now fully focus on opening ilani in late April or early May for the Cowlitz people so they can provide for their citizens.”

“To see it all come to fruition is really, really rewarding,” said Mitchell Etess, chief executive officer of the Mohegan Tribal Gaming Authority. “Everybody’s happy for the Cowlitz Tribe. ... For us, we’re expanding to the West Coast — it broadens our reach and diversifies our cash flow.”

The Mohegans and the Cowlitz forged development and management agreements in 2004.

A federal judge dismissed opponents’ lawsuit against the project in 2014, prompting an appeal to the U.S. Court of Appeals for the District of Columbia, which upheld the dismissal. In October, the opponents asked the U.S. Supreme Court to take up the case, arguing that the federal government cannot take land into trust for tribes that gained federal recognition after 1934. The Cowlitz tribe was recognized in 2000.

The Cowlitz tribe secured construction financing for the project in 2015, and shortly thereafter joined the Mohegans in announcing that Kara Fox-LaRose, a Mohegan tribal member who began her career at Mohegan Sun in 1996, had been named general manager of the facility.

The Trump administration filed a brief last month in which it sided with the Cowlitz tribe in urging that the Supreme Court not hear the case.

In a statement, William Iyall, the Cowlitz tribal chairman, thanked Ryan Zinke, secretary of the U.S. Department of the Interior, which oversees Indian affairs, for his support.

“He has continued to carry the torch in defense of our lands — an effort that has now carried through three presidential administrations,” Iyall said of Zinke.

The Cowlitz tribe has completed a $32 million highway interchange project designed to facilitate casino traffic. The interchange was set to open Tuesday night.

b.hallenbeck@theday.com