Kooskia is a city in Idaho County, Idaho, United States. It is at the confluence of the South and Middle forks of the Clearwater River, co…Kooskia is a city in Idaho County, Idaho, United States. It is at the confluence of the South and Middle forks of the Clearwater River, combining to become the main river. The population was 607 at the 2010 census, down from 675 in 2000.