Boundary describes the extent of the Spokane Valley-Rathdrum prairie aquifer from south end of lake Pend Oreille, Idaho - thru Rathdrum Prairie, the Spokane Valley, turning north to discharge at little Spokane River, and Spokane river north and west of the city of Spokane. Source data overview:Spokane Valley aquifer (WA State only) digitized in 1988 by Spokane Co. Engineer Dept from USGS 1977 hydrologic study of the Spokane Aquifer. This layer digitized from 1:24000 quad maps into the County's GDMS GIS. The USGS relied heavily on contour lines that described the valley floor to delineate the Spokane aquifer boundary. The original boundary had the Spokane River as it's west edge, but was revised (by Bea Leckaff Spokane County WQMP-GIS) in June, 1994, under the direction of Stan Miller to include the flood plain terraces on the west side of the river, down to the Little Spokane River confluence. The extent of the aquifer was revised again in March, 1995 to reflect new information from CH2MHill aquifer studies being done for the City of Spokane (to support Wellhead Protection). The revised aquifer extends the influence of impervious basalt outcroppings from the Spokane Falls area to the Trinity Triangle, (Drumheller Springs). The corrections were made by BBL from information provided by Stan Miller.

Idaho Portion of the Aquifer data came from Idaho Panhandle Public Health GIS SCALE: Idaho data digitized originally from 1:24000 USGS maps LAST UPDATED: March 1993- received Idaho data and matched to Spokane county aquifer data.

The TIGER/Line shapefiles and related database files (.dbf) are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER/Line shapefile is designed to stand alone as an independent data set, or they can be combined to cover the entire nation. The All Roads Shapefile includes all features within the MTDB Super Class "Road/Path Features" distinguished where the MAF/TIGER Feature Classification Code (MTFCC) for the feature in MTDB that begins with "S". This includes all primary, secondary, local neighborhood, and rural roads, city streets, vehicular trails (4wd), ramps, service drives, alleys, parking lot roads, private roads for service vehicles (logging, oil fields, ranches, etc.), bike paths or trails, bridle/horse paths, walkways/pedestrian trails, and stairways.

Rathdrum Comprehensive Aquifer Management Area Plan (CAMP) boundary of the Spokane Valley-Rathdrum Prairie Aquifer clipped at the Idaho border. Original boundary describes the extent of the Spokane Valley-Rathdrum Prairie aquifer from south end of lake Pend Oreille, Idaho - thru Rathdrum Prairie, the Spokane valley, turning north to discharge at little Spokane river, and Spokane river north and west of the city of Spokane. Spokane Valley aquifer (WA State only) was originally digitized in 1988 by Spokane Co. Engineer Dept from USGS 1977 hydrologic study of the Spokane Aquifer. This layer digitized from 1:24000 quad maps into the County's GDMS GIS. It was modified in June 1994 by Spokane County WQMP-GIS and again in March 1995 based on data from additional aquifer studies conducted by CH2Mhill. The Idaho portion of the Aquifer data came from Idaho Panhandle Public Health GIS in March 1993. The Aquifer boundary was redrawn based on new data from a coordinated ground and surface water monitoring program conducted in 2004-2005. The study reassessed the hydrogeology and water budget of the Spokane Valley-Rathdrum Prairie Aquifer (Aquifer). Data was originally digitized at a 1:24000 scale.