The Willamette Lowland basin-fill aquifers (hereinafter referred to as the Willamette aquifer) is located in Oregon and in southern Washington. The aquifer is composed of unconsolidated deposits of sand and gravel, which are interlayered with clay units. The aquifer thickness varies from less than 100 feet to 800 feet. The aquifer is underlain by basaltic-rock. Cities such as Portland, Oregon, depend on the aquifer for public and industrial use (HA 730-H). This product provides source data for the Willamette aquifer framework, including: Georeferenced images: 1. i_08WLMLWD_bot.tif: Georeferenced figure of altitude contour lines representing the bottom of the Willamette aquifer. The original figure was from Professional Paper 1424-A, Plate 2 (1424-A-P2). The contour lines from this figure were digitized to make the file c_08WLMLWD_bot.shp, and the fault lines were digitized to make f_08WLMLWD_bot.shp. Extent shapefiles: 1. p_08WLMLWD.shp: Polygon shapefile containing the areal extent of the Willamette aquifer (Willamette_AqExtent). The original shapefile was modified to create the shapefile included in this data release. It was modified to only include the Willamette Lowland portion of the aquifer. The extent file contains no aquifer subunits. Contour line shapefiles: 1. c_08WLMLWD_bot.shp: Contour line dataset containing altitude values, in feet, referenced to National Geodetic Vertical Datum of 1929 (NGVD29), across the bottom of the Willamette aquifer. These data were used to create the ra_08WLMLWD_bot.tif raster dataset. Fault line shapefiles: 1. f_08WLMLWD_bot.shp: Fault line dataset containing fault lines across the bottom of the Willamette aquifer. These data were not used in raster creation but were included as supplementary information. Altitude raster files: 1. ra_08WLMLWD_top.tif: Altitude raster dataset of the top of the Willamette aquifer. The altitude values are in meters reference to North American Vertical Datum of 1988 (NAVD88). The top of the aquifer is assumed to be land surface based on available data and was interpolated from the digital elevation model (DEM) dataset (NED, 100-meter). 2. ra_08WLMLWD_bot.tif: Altitude raster dataset of the bottom of the Willamette aquifer. The altitude values are in meters reference to NAVD88. This raster was interpolated from the c_08WLMLWD_bot.shp dataset. Depth raster files: 1. rd_08WLMLWD_top.tif: Depth raster dataset of the top of the Willamette aquifer. The depth values are in meters below land surface (NED, 100-meter). The top of the aquifer is assumed to be land surface based on available data. 2. rd_08WLMLWD_bot.tif : Depth raster dataset of the bottom of the Willamette aquifer. The depth values are in meters below land surface (NED, 100-meter).