Endemic to the upper Klamath River Basin (Miller, Evening, Jack, and Long creeks, and upper reaches of the Williamson and Sycan rivers), Oregon (Ref. 89241). Formerly endemic to the Miller Lake, Klamath County in Oregon. Purposely exterminated from Miller Lake because of its predation on introduced trout (Ref. 5723). Thought to have been extinct; surveys conducted in 1997-1999 reconfirmed the species extinction in Miller Lake but led to the discovery of several subpopulations within and outside the Miller Lake sub-basin (Ref. 81231). Its status has improved since 1989 listing of endangered species (Ref. 81264).

Status of threat: endangered. Criteria: 1,2,5 (http://fisc.er.usgs.gov/afs/) (Ref. 81264).