Transmissivity of the Principal Aquifer, Nebraska (GM-65.x), 1 Sheet, (1:250,000; 2005). Size 30" x 24". Description:These maps shows lines of equal transmissivity in thousands of gallons per day per foot for the principal aquifer system. The map also show where the principal aquifer is thin or absent. The term transmissivity is used to represent the capacity of the entire thickness of the aquifer to transmit water. High transmissivity areas, generally greater than 100,000 gallons per day per foot (gpd/ft), correspond to areas where the aquifer is thick and/or consists of coarse deposits of sand and gravel. Low transmissivity areas, generally less than 20,000 gpd/ft, correspond to areas where the subsurface material has low hydraulic conductivity such as glacial till and/or areas where the aquifer is thin such as high bedrock locations. These regional-scale maps are intended to be used for regional understanding of hydrologic conditions and should not be substituted for detailed site-specific decision-making activities with economic or legal implications. They can be used as a “first-cut” of information prior to local site-specific hydrogeologic investigations. For more detail on how these maps were made and their intended uses and limitations refer to Open File Report 71 (OFR-71). Print on Demand, select the map for your area of interest, price will then be added.