WCT Multi-State Assessment February 10, 2003 



Part 1 -- Historical Distribution 



The historically occupied range of WCT will be assessed based on their believed distribution at the time 

 Europeans first entered the Rocky Mountain West (approximately 1800. . This assessment will be done at a 

 relatively coarse level. Fourth-code level Hydrologic Units will be used for accounting purposes. The 

 1: 100,000 hydrography layer will be used to maintain consistency of information. Fishery professionals 

 fr.miliar with each major drainage basin (Fourth-code HUC) will define historical distribution for stream 

 mapping segments within each 4' code HUC by identifying the historical range based on their personal 

 knowledge of the area, known anecdotal information, known habitat restrictions, known geologic barriers, and 

 historical fisheries data and reports. This information will be used to edit WCT historical range maps at the 

 1 : 100,000 scale. WCT will be assumed to have occupied all streams within their broad known historical 

 distribution unless information or professional judgment indicates WCT likely did not occupy .specific mapping 

 segments of stream based on a documented rationale (Table 3). Data sources used to determine whether stream 

 segments were historically occupied, or not occupied, will be provided (Table 2), along with a reference 

 documenting why each stream segment was included or excluded, when applicable. 



Table 3. Look-up table for reasons to exclude or include a stream segment as historical WCT habitat. 



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