The Koi Nation of the Lower Lake Rancheria is a federally recognized tribe of Southeastern Pomo people in northern California.

In 1856, the US government forcibly removed many Pomo people to a reservation in Mendocino County; however, the Koi remained on their island.

[citation needed] By the beginning of the 1900s, tribal members were primarily living around Santa Rosa, Windsor, and Sebastopol.

[citation needed] Records on file at the National Archives regional center in San Bruno show that in 1953, when Lake County expressed interest in acquiring the land for an airport, the only two Indians living on Purvis Flats were a couple, Harry Johnson and his wife, Isabella.

[7] Indian Health program records similarly show termination as of that date, with no tribal members eligible for services.

[9] After years of attempting to have their status reaffirmed, the Bureau of Indian Affairs, "citing oversights in official records",[9] again recognized the tribe on December 29, 2000.

The tribe argued that a full CEQA environmental review was required, instead of a mitigated negative declaration by the city.

[citation needed] In 1994, a new tribal government apparently was formed to make a claim for Pearce Field,[5] a small airport which Lake County closed that year.

[17]: 378 In 2005, the tribe officially announced its plans to build a world-class tribal government gaming facility, resort and spa near the Oakland International Airport.

The Tribe also began talks with the city to explore potential benefits the project could bring to the local economy.

[25] Koi Nation attorneys filed an application to place the land into trust with the federal government, to make it eligible for casino construction under the Indian Gaming Regulatory Act.

The agreement calls for Global Gaming Solutions, a wholly-owned Chickasaw business, to manage and operate the proposed facility.

[28] In February 2022, the tribe announced an agreement with the Northern California Carpenters Union, for the site, which is planned to have 2,500 gaming machines, a 400-room hotel, six restaurant and food service areas, a meeting center and spa, and a live entertainment venue.

[30] The EA was issued in late 2023; in March 2024, the BIA decided that an environmental impact statement (EIS), a more comprehensive assessment, was required.