WCT Multi-state Assessment February 10, 2003 



Methods 



We developed a standardized approach and consistent protocols that were used by all 

 participants (Appendices A and B). Information was gathered and entered into geographic 

 infonnation system (GIS) and relational databases by having fishery professionals participate in 

 facilitated workshops by geographic area. Many different sources of information were used in 

 this assessment, but consistency was maintained by having one or two individuals attend all 

 workshops and facilitate data entry and answer questions raised by workshop participants. Since 

 this assessment relied upon existing information, sampling was not random, and in many cases 

 not independent; therefore, there are undoubtedly biases associated with these data. We discuss 

 the possible consequences of these biases when we present the results. We have attempted to 

 qualify and disclose the quality of these data through citations and by having the people that 

 provided information rate the relative data quality for each part of this assessment from 1 

 (primarily based on professional judgment) to 3 (field survey information). 



Geographic Information System 



We used the 4th code hydrologic unit code (8-digit EPA designation) as the primary unit for 

 organizing data input from the fisheries professionals. We also summarized historical range and 

 current status information using this stratification. The U.S. Geological Survey (USGS) created 

 the hierarchical hydrologic unit code (HUC) system for the United States in the 1970"s. This 

 system divides the country into 21 Regions, 222 Sub-regions, 352 Accounting Units, and 2,149 

 Cataloging units based on surface hydrologic features. The smallest HUC used in this study was 

 approximately 448,000 acres (Hydrologic Units Maps of the Conterminous United States. 

 Reston, VA. United States Geological Survey. August 2002. http://water.usgs.gov/GIS/metadata/ 

 usgswrd/huc2 5 Ok.html ). 



We chose to use stream and river distance as measures of WCT occupancy, both for suspected 

 historical and known currently occupied habitats. Consequently, lake occupancy was not 

 directly assessed; however, all lakes that were located within the stream network were included, 

 as length values, if the stream network bisected the lake. Our assessment update used GIS tools 

 in Arcview 3.2 along with extensions created for this project (Steve Carson, Montana Fish 

 Wildlife and Parks, Helena, Montana modified "ddeaccess.avx" and "routetool.avx" extensions 

 that are available from ESRI at http://arcscripts.esri.com) as well as a relational database within 

 Microsoft Access (modeled after the Montana Fish Wildlife and Parks' MFISH database that can 

 be found at http://nris.state.mt.us/scripts/esrimap.dll?name=MFISH&Cmd=INST) for organizing 

 and displaying the data. 



A Latitude-Longitude Identifier (LLID) 1:100,000 hydrography layer that was edge-matched 

 across state boundaries was used as the primary base-layer. The U.S. Geological Survey (USGS) 

 in Portland, in cooperation with Bonneville Power Administration, the Northwest Power 

 Planning Council, and other Federal and state agencies and NW Indian Tribes produced a 

 1 : 100,000-scale River Reach data layer for the Pacific Northwest in the early 1990s. The Pacific 

 Northwest (PNW) River Reach Files are a geo-referenced river reach data layer that 

 encompasses the Columbia River Basin within the contemiinous United States, the coasts of 



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