This dataset has been deprecated. Please use our 2017 Countywide Contours instead.These data comprise of one foot contours showing the elevation of Lake County, IL corresponding to the orthometric heights of the bare surface of the county (no buildings or vegetation cover). These data were developed from LIDAR data obtained between April 16, 2007 and May 07, 2007, and further supplemented by break lines collected from aerial photography taken at the same time. The contours and the aerial photography meet National Map Accuracy Standards for a 1 inch = 100 foot product. The contours have been created to be cartographically pleasing, as such some generalization has been introduced as expected. The contours have been tested against the original LIDAR points and conforms to the American Society for Photogrammetry and Remote Sensing (ASPRS) Specifications and Standards Committee, 1990, ASPRS Accuracy Standards for Large-Scale Maps, CLASS 1 map accuracy. The vertical datum is the North American Vertical Datum of 1988.

The U.S. Army Corps of Engineers Engineering and Design Manual for Photogrammetric Production recommends that data intended for this usage scale be used for any of the following purposes: route location, preliminary alignment and design, preliminary project planning, hydraulic sections, rough earthwork estimates, or high-gradient terrain / low unit cost earthwork excavation estimates. The manual does not recommend that these data be used for final design, excavation and grading plans, earthwork computations for bid estimates or contract measurement and payment.

Contour data is used by county agencies to study drainage issues such as flooding and erosion. Customers interested in the actual LiDAR data may download it at no cost from the USGS Center for LiDAR Information Coordination and Knowledge.

These files are tiled by PLSS section and grouped by township and format for easier download. Please note that this dataset is available in for GIS in Esri shapefile format as well as for CAD in AutoCAD DWG and MicroStation DGN. We are unable to provide any support for CAD users beyond providing the data.