The U.S. Department of Interior has released a final environmental impact statement on the 151-acre site. The move begins a one-month comment period before the decision is formally recorded.
Mashpee tribal chairman Cedric Cromwell said Thursday that publication of the environmental statement is among the last remaining steps before a final federal ruling on the land-in-trust application.
The 2011 casino law gave the tribe initial exclusivity in southeastern Massachusetts. The state's gambling commission later agreed to accept applications from commercial casino developers in the region while monitoring the tribe's progress in securing federal approval.
The tribe would likely pay 17 percent of its gambling revenues to Massachusetts under a compact with the state.