IA DEM was produced from 1/3rd arc-second downloaded from viewer.nationalmap.gov/basic. The 3DEP 1/3rd arc-second DEMs, previously referred to as the National Elevation Dataset (NED), are derived from diverse source data, processed to a common coordinate system and unit of vertical measure. All 3DEP data are distributed in geographic coordinates in units of decimal degrees, and in conformance with the North American Datum of 1983 (NAD 83). All elevation values are provided in units of meters, and are referenced to the North American Vertical Datum of 1988 (NAVD 88) over the conterminous United States. For the LANDFIRE Elevation product, the 1/3 arc-second 3DEP DEM data were projected from geographic to Albers Equal Area, resampled to 30m spatial resolution, and clipped out to the IA 0k boundary.