In Grand County, ground water has been withdrawn primarily from two types of aquifers: fractured rock and unconsolidated deposits. Some of the better water-yielding rock units are grouped together into nine aquifers, including: the Lower Paleozoic aquifer, the Cutler aquifer, the Wingate aquifer, the Navajo aquifer, the Entrada aquifer, the Morrison aquifer, the Dakota aquifer, the Wasatch aquifer, and the Parachute Creek aquifer. This report summarizes published information regarding ground-water conditions in Grand County. During the preparation of this report we identified several types of information that are not presently available, but can be useful for evaluating ground-water resources, including: (1) structure contour maps showing the depth to aquifers, (2) isopach maps showing the thickness of aquifers, and (3) fracture domain maps showing the predominant orientations of rock discontinuities.

The purpose of this study is to provide tools for water-resource management and land-use planning; to accomplish this purpose we (1) characterize the relationship of geology to ground-water conditions in the Glen Canyon and the unconsolidated valley-fill aquifers, (2) classify the groundwater quality of the Glen Canyon (east of the valley only) and valley-fill aquifers to formally identify and document the beneficial use of ground-water resources, and (3) apply a ground-water flow model using a mass balance approach to determine the potential impact of projected increased numbers of septic-tank systems on water quality in the valley-fill aquifer and thereby recommend appropriate septic-system density requirements to limit water-quality degradation

"This CD-ROM contains a 30 page report with 22 page appendix, and seven maps at 1:15,000 to 1:30,000 scale in easily readable PDF format that address ground-water quality in Castle Valley's valley-fill aquifer and provide recommendations for septic tank soil-absorption-system density based on potential water-quality degradation associated with use of these systems. The maps are described in detail in the report and show geology, valley-fill thickness, total-dissolved-solids concentration, nitrate concentration, ground-water quality class, potential containment sources, and recommended lot size."--Sticker on back of case.

The U.S. Environmental Protection Agency is recommending that states develop Pesticide Management Plans for four agricultural chemicals – alachlor, atrazine, metolachlor, and simazine – herbicides used in Utah in the production of corn and sorghum. This report and accompanying maps are intended to be used as part of these Pesticide Management Plans to provide local, state, and federal government agencies and agricultural pesticide users with a base of information concerning sensitivity and vulnerability of ground water to agricultural pesticides in Utah. We used existing data to produce pesticide sensitivity and vulnerability maps by applying a combined process-based and index-based model specifically tailored to the Western United States using Geographic Information System analysis methods. This is a first cut at developing pesticide sensitivity and vulnerability maps; better data and tools may become available in the future so that better maps can be produced. 40 pages + 2 plates