The U.S. Geological Survey developed this dataset as part of the Colorado Front Range Infrastructure Resources Project (FRIRP). One goal of the FRIRP was to provide information on the availability of those hydrogeologic resources that are either critical to maintaining infrastructure along the northern Front Range or that may become less available because of urban expansion in the northern Front Range. This dataset extends from the Boulder-Jefferson County line on the south, to the middle of Larimer and Weld Counties on the North. On the west, this dataset is bounded by the approximate mountain front of the Front Range of the Rocky Mountains; on the east, by an arbitrary north-south line extending through a point about 6.5 kilometers east of Greeley. This digital geospatial dataset consists of digitized water-level-elevation contours.
This dataset was created by the U.S. Geological Survey (USGS) in the development of the USGS Front Range Infrastructure Resources Project. This dataset was used in the creation of 1:50,000-scale hydrogeologic contour maps. It also was used as an input source for the automated generation of a water-level-elevation surface that was in turn used to generate an unsaturated-zone-thickness (depth-to-water) surface, also contoured for use in 1:50,000 maps.
Water-level-elevation data from well logs (see "Lineage" section) were manually plotted and contoured onto mylar overlays of 45 paper USGS 7.5-minute topographic series quadrangle maps that encompass the Colorado Front Range Infrastructure Resources Project area. The mylar overlays were scanned into Tagged Image File Format (TIFF) image files that were then converted into Arc/INFO raster datasets known as grids. The grids were converted into vector datasets known as coverages in Arc/INFO-specific terminology. Arc items "CONTOUR" and "DASH" were added to the arc attribute table of the coverage and manually attributed in Arcedit, using the original manuscript mylars for references. The coverages were then projected into a common map coordinate system and edgematched. The northern and eastern areas of each coverage were edgematched when necessary: the linework of the northern edge of a coverage was adjusted to fit the linework of the southern edge of a coverage adjacent to the north; the linework of the eastern edge of a coverage was adjusted to fit the linework of the western edge of a coverage adjacent to the east. The linework from each coverage was appended into a single coverage in which dangling vectors less than 12.192 meters long were removed and in which vector vertices and nodes within 1.2192 meters of each other were merged. The coverage was built with line topology. Linework extends beyond the southern edge of the study area for consistency with previous work in that area (Robson, 1996). The final coverage in intended to be used as one thematic layer in maps to be published at a scale of 1:50,000. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
publication date
This dataset should not be used at a scale larger than 1:50,000.
PO BOX 25046 MS 415
Chain-node topology, as verified by ESRI Arc/INFO v. 7.x BUILD, is present.
Information concerning completeness that is not contained in the Supplemental_Information element can be found in Robson and others (2000a, 200b, 2000c, 2000d).
Maps of water-level elevation were prepared at 1:24,000 by hand-contouring data with 10- and 20-foot-contour intervals. These maps were produced directly from data and for the purposes of this study are considered to be first-order maps with a vertical accuracy of about 10 feet, or about 3 meters.
No tests were performed to verify the Vertical Positional Accuracy Value.
lithologic and water-level data
lithologic data
lithologic data
lithologic data
lithologic data
lithologic data
lithologic data
lithologic data
water-level data
lithologic data
water-level data
lithologic data
lithologic data
lithologic data
lithologic and water-level data
lithologic and water-level data
water-level data
water-level data
lithologic data
water-level data
water-level data
water-level data
lithologic data
water-level data
lithologic data
water-level data
lithologic data
lithologic data
lithologic data
lithologic and water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
unknown
unknown
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
lithologic data
water-level data
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
water-level data
lithologic data
lithologic data
unknown
lithologic data
lithologic data
lithologic data
lithologic data
lithologic data
lithologic data
lithologic data
lithologic and water-level data
lithologic data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
water-level data
lithologic data
water-level data
lithologic data
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
lithologic and water-level data
See Supplemental Information.
Internal feature number.
ESRI
Feature geometry.
ESRI
Internal node number for the beginning of an arc (from-node).
ESRI
Internal node number for the end of an arc (to-node).
ESRI
Internal node number for the left polygon.
ESRI
Internal node number for the right polygon.
ESRI
Length of feature in internal units.
ESRI
Internal feature number.
ESRI
User-defined feature number.
ESRI
Water-level elevation, in feet above sea level.
U.S. Geological Survey
One-character-wide key used in hardcopy production, indicative of the locational accuracy of the line.
U.S. Geological Survey
Uncertain line location--line, when plotted, should be dashed.
U.S. Geological Survey
Well-defined line location--line, when plotted, should be solid.
U.S. Geological Survey
Water-level elevation, in meters above sea level.
U.S. Geological Survey
Water-level elevation, in meters above sea level.
U.S. Geological Survey
507 National Center
Although this data set has been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data and related materials. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Hydrogeologic contours geographic features
Hydrogeologic contours geographic features
ArcIMS Image Map Service
A web-based interactive mapping system that accesses an ArcIMS Map Service running on certmapper.cr.usgs.gov.
Full coverage
Shape file
507 National Center