The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Oncorhynchus clarkii lewisi
Oncorhynchus clarkii lewisi
(Westslope Cutthroat Trout)
Native Transplant

Copyright Info
Oncorhynchus clarkii lewisi (Girard, 1856)

Common name: Westslope Cutthroat Trout

Taxonomy: available through www.itis.govITIS logo

Native Range:
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Oncorhynchus clarkii lewisi are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CO197419934Colorado Headwaters; Rio Grande Headwaters; South Platte; Upper Arkansas
ID1981201141Big Lost; Big Wood; Boise-Mores; Camas; Clearwater; Coeur d'Alene Lake; Hells Canyon; Lemhi; Little Lost; Little Salmon; Little Wood; Lochsa; Lower Clark Fork; Lower Kootenai; Lower Middle Fork Salmon; Lower North Fork Clearwater; Lower Salmon; Lower Selway; Middle Kootenai; Middle Salmon-Chamberlain; Middle Salmon-Panther; Moyie; North and Middle Forks Boise; North Fork Payette; Pahsimeroi; Payette; Pend Oreille Lake; Priest; Raft; South Fork Boise; South Fork Clearwater; South Fork Coeur d'Alene; South Fork Payette; South Fork Salmon; St. Joe; Upper Middle Fork Salmon; Upper North Fork Clearwater; Upper Salmon; Upper Selway; Upper Spokane; Weiser
MI196419641Great Lakes Region
NV192519622Great Basin; Walker Lake
OR197319731Upper John Day
WA193519993Pacific Northwest Region; Priest; Puyallup

Table last updated 5/30/2024

† Populations may not be currently present.

* HUCs are not listed for states where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Means of Introduction: Stocked for sport

References: (click for full references)

Marotz, B. 2004. Tough Love, why it makes sense to kill some fish in order to save others. Montana Outdoors. March/April 2004.

Schultz, L. P. and A. C. DeLacy. 1935. Fishes of the American Northwest. Journal of the Pan-Pacific Research Institution. Vol. X, No. 4, 365-380.

Tilmant, J.T. 1999. Management of nonindigenous aquatic fish in the U.S. National Park System. National Park Service. 50 pp.

Other Resources:
FishBase Summary

Revision Date: 7/1/2019

Peer Review Date: 3/25/2010

Citation Information:
U.S. Geological Survey, 2024, Oncorhynchus clarkii lewisi (Girard, 1856): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=895, Revision Date: 7/1/2019, Peer Review Date: 3/25/2010, Access Date: 5/30/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [5/30/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.