Major layer updates added to this disc include karst features, soils, hydrography and bridges. The karst features were developed by PA DCNR and include the location of sinkholes, surface depressions and caves. The soils layer was developed by NRCS and contains information from the Soil Survey Geographic Database (SSURGO) that provides for consistent mapping of soil features in both counties, including slope and prime agriculture. The hydrography layer was created by the USGS and PA DEP and includes data from the National Hydrography Dataset (NHD). This layer provides for the consistent mapping of hydrography features in each county, including streams, lakes/ponds and rivers; and supports the mapping of other hydrography attributes as necessary. The bridges layer was updated by the LVPC and contains new information released by PennDOT in 2007, such as bridge structural condition and sufficiency ratings. There are 26 layers on this disc that were updated to be more current than on the prior disc, and most are updated through December 2007. It’s recommended that you check the layer metadata for the date the layer was last updated. In total, 62 layers are on the data disc and all are in the ESRI shape file format. The data is in the same geographic coordinate system as the data available from Lehigh and Northampton counties, so the data can be overlaid with the county’s data for easy viewing and mapping in a GIS.

A list of GIS layers provided on this disc is on the back cover of the CD insert. The GIS layers can be accessed using ESRI ArcView, ArcGIS or other GIS software that reads the ESRI shape file format. The user of this disc should have enough of an understanding of the ESRI GIS software to load the layers into a view. In addition, this disc contains a data dictionary that describes information about each data layer and that can be viewed using any standard Internet browser software.

The data included on this disc are from twelve sources: Lehigh Valley Planning Commission (LVPC), Pennsylvania Department of Transportation (PennDOT), Northampton County Department of Fiscal Affairs (GIS Division), Lehigh County Tax Assessment Department, Natural Resources Conservation Service (NRCS), Pennsylvania Department of Conservation and Natural Resources (PA DCNR), Federal Emergency Management Agency (FEMA), The Pennsylvania Natural Heritage Program (PNHP), United States Fish & Wildlife Service (USFWS), U.S. Census Bureau, Pennsylvania Department of Environmental Protection (PA DEP) and the United States Geological Survey (USGS). All the data are in the State Plane Pennsylvania-South geographic coordinate system and the horizontal control is on the North American Datum of 1983. Data from these different sources will not be fully compatible due to differences in original mapping scale, mapping source, method of digital construction or other reasons. The NRCS, PNHP, USFWS, PA DEP, PA DCNR and USGS data are compiled from 1" = 2000’ quadrangle mapping provided by USGS. Lehigh and Northampton County data are compiled from 1" = 400’ and 1" = 200’ aerial photography depending on the scale of the county’s tax map sheets. The U.S. Census, FEMA and PennDOT data were re-compiled to the same mapping scale as both counties. Data created at the county’s mapping scale is more accurate than some other data since it was compiled at a larger scale. When you overlay data compiled from the county with some other source data you will see instances of this. For example, at various locations traffic analysis zone features do not stay within the right-of-way of the County’s parcel data. It is the responsibility of the user to refer to the data dictionary for the accuracy of any particular spatial data layer and its associated attributes.

Digital Raster Graphic (DRG) images are available on a separate disc from the LVPC. A DRG is a raster image of a scanned USGS 7.5 minute topographic map excluding the collar information. The DRG images will be in the same geographic coordinate system as the data on the data disc. No changes have been made to the DRGs since the prior release.

Different versions of aerial photography are available on separate discs from the LVPC that cover the entirety of Lehigh and Northampton counties. This data is in the same geographic coordinate system as the data on the data disc. One version is natural color orthophotos captured in April 2005 at 1"=200’ design scale and 1’ pixel resolution. The other version is black/white Digital Orthophoto Quarter Quad (DOQQ) photography captured in 1992/1993 at 1-meter pixel resolution. Each DOQQ file covers one quarter of a standard USGS quadrangle sheet (see quadrangle boundary index shape file included within this disc). Orthophoto refers to a process of correcting the photography for topographic distortion to create photography where features are located in their true ground position.

This CD case contains two discs. The first disc has two directories that include:

Shapes — This directory includes all the GIS layers in ESRI shape file format, and the associated legend and projection files for the shape files. The legend files contain a predefined graphic representation of the shape file features. The legend files have the same name (e.g. floodplains, bridges) as the shape files. The legend files with an ".avl" extension are created for the ArcView 3.x software, and the ones with a ".lyr" extension are for the ArcGIS 9.x software.

Data Dictionary — This directory includes information describing each spatial layer and its associated attributes, including the date the layer was last updated. The table of contents for the data dictionary is accessed using the "index.htm" file, which provides links to all the other data dictionary information. Internet browser software such as Microsoft Internet Explorer can be used to view this data.

The second disc has one directory that includes:

Shapes — This directory includes the topographic contours layer. This layer was too large to fit on the first disc.

Note that the user may access and use the data on this disc directly from the CD drive. However, copying the data to the computer hard drive will improve the speed of loading and using the data in ArcView or ArcGIS software.

The LVPC will be offering new and updated GIS layers in later disc releases. Please contact Alice Lipe at 610-264-4544 or e-mail (lvpc@lvpc.org) to purchase this CD, or if you have any data-related questions please refer to the layer contact information in the data dictionary, or contact Lynette Romig at 610-264-4544 or e-mail at (ler@lvpc.org).

Northampton County (Only)
Hydrology – Polygons
Hydrology – Lines