The subsample theme group contains data sets that were compiled by sampling conditions for a subset of subwatersheds within the Basin. Terrestrial and hydrologic criteria were used to stratify watersheds for sampling and characterization. Data was collected for the subsample areas for vegetation (historic and current), valley bottom settings and roads. These themes are not continuous in extent but were collected for representative areas. Sources for the subsample data sets were from the field units or were completed by contract. Much of the data came from aerial interpretation of historic and current photos. The subsample data sets were crucial for characterizing and describing the mid-scale vegetation, biophysical environment and extrapolation of this information to unsampled areas across the Basin.