BILLINGS (AP) — The U.S. Senate Indian Affairs Committee approved a $420 million water rights settlement with Montana's Blackfeet American Indian tribe on Wednesday, sending the measure to the full Senate.

The settlement proposes to rehabilitate the Four Horns Dam and Blackfeet Irrigation Project and make other improvements on the Blackfeet tribe's Montana reservation.

Negotiations on the agreement began more than 30 years ago. It was approved by the Montana Legislature in 2009.

Prior attempts to advance the settlement through Congress failed, after the administration of President Barack Obama objected to its original price tag of $591 million.

The latest version is sponsored by Democratic U.S. Sen. Jon Tester and Republican U.S. Sen. Steve Daines.

Both Tester and Daines said during a Tuesday committee meeting that they would seek ways to offset the cost of the settlement. Neither offered specifics.

Tester offered revisions to the bill that he said resulted from negotiations involving the tribe and federal officials. He said it would provide the tribe with healthy drinking water and help boost economic development on a reservation that suffers from rampant poverty and unemployment.

"This is the first time we're passing this bill out of committee, so it is a step in the right direction," Tester said.

The tribe must approve the settlement before it can become effective.

It would require the tribe to waive its legal claims against the federal government over water disputes dating back a century. Those include the government's past failures to protect the tribes water rights, the diversion of water off the reservation for a government irrigation project and environmental damages caused by that diversion.

The Senate measure was opposed by Sen. John Hoeven, a Republican from neighboring North Dakota.

Hoeven expressed concern over its potential consequences for any future water agreements between Montana and North Dakota. Hoeven said the attorneys general of the two states have been in negotiations over the matter but have not resolved it.