The map was made for cartographic display of tribal lands at a small scale. Data from two sources of radically different scales were combined--federal boundaries at 1:2 million (fed2m) from ARCUSA and the ownership cover (own) compiled at the state level by the project, generally originating from sources at around 1:100,00 scale. Fed2m reservations tend to be shown as continuous blocks, while own data tend to show the fragmented nature of some reservations. In cases of discrepancies between fed2m and own, a boundary encompassing both portrayals was generally used. Thus this map tends to overestimate reservation area. For some areas derived from the own cover, unattributed polygons within reservations represent inclusions of non-tribal ownership, lakes, etc. However data derived from the fed2m cover are generalized to the degree that such inclusions are not portrayed at all.
Geographic Information System (GIS) data layers or themes were compiled or created in support of the ICBEMP Assessment and the development of the Eastside and Upper Columbia River Basin Environmental Impact Statements. The themes were derived from source maps, photos, or transfer media ranging from 1:12,000 to 1:4,000,000 in scale. Some GIS themes mapped features continuously across the entire project area while others covered discrete areas only (e.g. subsample watershed areas). Major data providers included individual administrative units of the Forest Service, Bureau of Land Management, U.S. Fish and Wildlife Service, Environmental Protection Agency, U.S. Geological Survey, U.S. Bureau of Mines, Bonneville Power Administration, universities, state agencies, American Indian tribes, and non-governmental organizations.
The ICBEMP cannot assure the reliability or suitability of this information for a particular purpose. Original data was compiled from various sources. Spatial information may not meet National Map Accuracy Standards. This information may be updated without notification.