Gov. Deval Patrick signed a compact with the Mashpee Wampanoag tribe on Monday, cementing a deal to grant the Mashpee tribe an exclusive casino license for southeastern Massachusetts over the Wampanoag Tribe of Gay Head (Aquinnah).

The Mashpee tribe plans to build a $500 million casino and resort in Taunton, with a payout of 21.5 per cent of gross gaming revenues to the state over 15 years. The agreement was negotiated by Gov. Patrick and ratified by the state legislature late last week; the Mashpee tribal council approved the agreement on July 11. The tribe still needs approval from the U.S. Department of the Interior for the federal government to take land into trust on behalf of the tribe. The department has 45 days to review the application.

“I thank the legislature for approving the compact with the Mashpee Wampanoags,” Governor Patrick said in a statement after the signing on Monday. “This is an important milestone and a good deal for both the commonwealth and the tribe. It respects the inherent rights of the tribe while adhering to the principles set forth in the Expanded Gaming Act. Now we turn our attention to the federal government and final approval of the compact and the tribe’s land in trust application.”

Mashpee was working against a July 31 deadline to satisfy the state’s gaming law, which was enacted late last year and which authorized the governor to issue three resort-style casino licenses in the state. One of the licenses was reserved for a federally-recognized American Indian tribe. The Massachusetts Gaming Commission, the body formed to oversee the new law, will issue pre-qualifying regulations for the remaining two licenses for commercial bidders in October.

The signing with the Mashpee tribe is the latest blow for the Wampanoag Tribe of Gay Head (Aquinnah), which was also vying for a Class III casino license in the southeastern region of the state. Gov. Patrick refused to negotiate with the Vineyard tribe, citing a 1983 land claims settlement in which the tribe waived its sovereignty. Earlier this month, the Vineyard tribe announced its intention to sue the state, and possibly also the town of Aquinnah, to protect its right to build a casino on the mainland and on the Vineyard. The Vineyard tribe has argued that the federal Indian Gaming Regulatory Act trumps state law and the sovereignty agreement.

In May, voters in Lakeville and Freetown dealt the Aquinnah tribe another blow when they decisively voted in nonbinding referendums against bringing a casino to land spanning those two towns.

By contrast, the Mashpee tribe has gained approval at every turn, first through strong voter support at a referendum vote taken in the spring, and then again when Gov. Patrick announced plans to enter into an agreement with the tribe earlier this summer.

The Vineyard tribe has criticized the agreement between the Mashpee tribe and the state, and called “the concession” to pay the state more than 20 per cent of its gross pay “unjust and burdensome.” But at the signing on Monday, the speaker of the house, Robert A. DeLeo defended the agreement.

“I commend Governor Patrick for his negotiation with the Mashpee Wampanoag tribe on what is a very strong and fair compact,” he said in the statement. “While these terms are in the best interest of both the commonwealth and the tribe, this compact represents another step forward for Massachusetts’ economy.”

Chairman of the Vineyard tribe Cheryl Andrews-Maltais could not be reached for comment.