Scale of Assessment
The assessment team used the California Watershed Map (CalWater version 2.2.1) to delineate the basins and subbasins for assessment and analyses purposes. The study areas are further delineated into smaller, functional ecological units; the descending order of scale is from basin level (e.g. SF Eel River Basin) to subbasin level (e.g., Northern Subbasin) to watershed level (e.g., Bull Creek) to sub-watershed level (e.g., Upper Bull Creek). Demarcation in this logical manner provides a common scale for conducting assessments. It also allows for reporting of findings and making recommendations for watershed improvement activities that are generally applicable across relatively homogeneous areas. Findings and recommendations are broader at the basin level and more specific at the sub-watershed level.
CalWater was created by the California Interagency Watershed Mapping Committee (IWMC), a collaboration of nine state and federal agencies. Since 2000, the IWMC has supported the development of a new dataset known as the Watershed Boundary Dataset (WBD). This new dataset is nationally consistent, and is delineated and geo-referenced to the USGS 1:24,000 scale. The WBD is now part of the USGS National Hydrography Dataset (NHD), and will eventually replace CalWater. Future CWPAP watershed assessments may use WBD to delineate planning watershed units. For additional information on WBD and the transition from CalWater, see: http://nhd.usgs.gov/wbd.html.