This data is ordered by the WADNR numbering scheme,.i.e. by row and column. Each 7.5' quad has a unique ID number. The first two digits of the ID number count down from 49 degress. The last two digits count east from 125 degrees.

Most 10-meter DEMs (designated with a D in the Zunit column) were created with elevations in integer decimeters. Decimeters excede the absolute accuracy, but they prevent stairstepping in low-slope areas. Depending on your software, they may import in decimeters, integer meters, or floating-point meters. Some DEM in southwest Washington (designated with an f in the Zunit column) were created with vertical units of feet. The comment field may contain information about the original photos, the software, the contour interval, and whether streams were used in creating the DEM.

These Digital Elevation Models are derived from the digitized contour lines (at 40' or smaller intervals) on the 7.5' (1:24000) quad sheets.