Koi was the more southerly of the two main Pomo villages in the southeastern section of Clear Lake in Lake County, California, USA. Both it and the other triblet center, Elem, were located on islands near the shore and controlled territory on the mainland. It was located on Lower Lake Island, also called Indian Island.
- Barrett, Samuel (1908). Frederick Ward Putnam (ed.). The Ethno-Geography of the Pomo and Neighboring Indians. University of California Publications in American Archaelogoy and Ethnology. 6. Berkeley: The University Press.
- U.S. Geological Survey Geographic Names Information System: Koi, California