Geospatial database of ground-water altitude and depth-to-ground-water data for Utah, 1971-2000

The U.S. Geological Survey (USGS), in cooperation with the Utah Department of Environmental Quality
has developed a geographic database of selected ground-water-level altitude contours and surfaces for
Utah. The contour data are derived from studies published by the USGS and the State of Utah. The
published contours were converted to digital format and attributes documenting information such as the
water-level altitude, the year the study report was published, the year for which the contours were drawn,
and a link to the on-line version of the study report were added to the data set. The contours were input
to the database as a unique polyline feature class for each study area. The digital contours were passed
through an inverse distance weighted algorithm to develop a continuous interpolated water-level altitude
surface in raster format. The water-level altitude surface was subtracted from USGS National Elevation
data to derive a second raster of the estimated depth-to-ground-water surface for each study.

Comparison of the derived water-level altitude surface to water-level measurements from the USGS
National Water Information System (NWIS) database shows calculated values from the water-level
altitude rasters are generally well correlated with measured values from NWIS.

The database is not intended to result in exact predictions of the ground-water altitude or depth to
ground water for any location but can be used as a general guide to aid the management and
protection of ground-water resources in Utah.