- Range extends from the Sierra Nevada Mountains northeast into Nevada and Oregon.
- In California, the historic range includes Lake Tahoe and the Carson, Truckee, and Walker River basins. Reports from settlers in 1853 assert Lahontan cutthroat trout were abundant in the Susan River as well.
- Once occupied a vast range but are extirpated from nearly 95% of their native habitat in California.
- Inhabit a wide range of habitats from high-elevation mountain streams to lower-elevation and highly alkaline desert lakes.
Introduction of non-native trout and habitat alteration from human land use activities caused their extirpation from the majority of their former range. Most self-sustaining populations are located in isolated headwater streams and are the result of reintroduction efforts. State fish hatcheries have been increasing their production and stocking of Lahontan cutthroat trout to expand fishing opportunities for this species in accessible waters within their native drainage.