In 2004, the U.S. Geological Survey initiated a large-scale regional study of the Denver Basin aquifer system to evaluate the hydrologic effects of continued pumping and document an updated groundwater-flow model useful for appraisal of hydrologic conditions (Paschke, 2011). This data release includes spatial datasets used as input for a three-dimensional groundwater-flow model of the Denver Basin aquifer system. Spatial datasets were developed for six Denver Basin bedrock aquifers and five intervening confining units including, from oldest to youngest, the Laramie-Fox Hills aquifer (KLF), Laramie confining unit (KLC), lower Arapahoe aquifer (LKA), Arapahoe confining unit (KAC), upper Arapahoe aquifer (UKA), Denver lower confining unit (TKDLC), Denver aquifer (TKD), Denver upper confining unit (TKDUC), lower Dawson aquifer (LTDW), Dawson confining unit (TDWC), and upper Dawson aquifer (UTDW). Maps of the base altitude and lateral extent of each aquifer were developed for the 11 aquifer and confining units to define the hydrogeologic framework for the model. The BasePoints.zip folder contains 11 point shapefiles of the data points for altitude of the base of each bedrock aquifer and confining unit and one shapefile with locations of wells in the Denver Basin having geophysical logs ("PP1770_seo_geologs_points"). The "BaseContours.zip" folder contains 11 polyline shapefiles of generalized lines of equal base altitude for each bedrock aquifer and confining unit derived from the base-altitude points, and the "Extents.zip" folder contains 11 polygon shapefiles representing the extent of each aquifer and confining unit. Maps of silt-plus-sand thickness were developed for the six bedrock aquifers and were used to estimate hydraulic conductivity and specific yield in the groundwater-flow model. The "SandPoints.zip" folder contains six point shapefiles of data points for silt-plus-sand thickness of each bedrock aquifer, and the "SandContours.zip" folder contains six polyline shapefiles of generalized lines of equal silt-plus-sand thickness derived from the silt-plus-sand thickness points. Shapefiles in the zipped folders are named using the abbreviation or name of the aquifer or confining unit as shown on Table A2 of Paschke (2011).

This data set represents the extent of the Denver Basin aquifer system in Colorado.

This data set represents the extent of the Denver Basin aquifer system in Colorado.

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 saturated-thickness polygons that were generated with a Geographic Information System (GIS).

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 saturated-thickness polygons that were generated with a Geographic Information System (GIS).

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 saturated-thickness polygons that were generated with a Geographic Information System (GIS).

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 depth-to-water (unsaturated-thickness) contours that were generated from hydrogeologic data with Geographic Information System (GIS) software.

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 bedrock-outcrop outlines from hand-drawn maps.

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.

The upper portion of the Troublesome Aquifer is the sole source of water for domestic use in the Greater Pole Creek Basin, situated in the western portion of the upper Fraser River Valley in Grand County, Colorado. Data from drilling records for wells installed near and within recent home developments, municipal water-suppliers, water-quality records, and published reports are summarized as an initial synthesis of aquifer water quantity and quality. In spite of persistent drought and increased domestic aquifer-water usage, aquifer water storage remains robust with water levels little changed during the past 25 years. Water-quality data indicate substantial variability with depth beneath the top of the aquifer. Data from wells completed in the overlying shallow alluvial aquifer are also presented for comparison. This document constitutes a new baseline for assessment of current and future groundwater resources within this portion of the upper Fraser River valley. Suggested future investigations include water-table monitoring and comprehensive water-quality surveys for water derived from wells completed in the Troublesome Aquifer.