Rocky Mountain Section - 61st Annual Meeting (11-13 May 2009)

Paper No. 5
Presentation Time: 9:20 AM

COMPILATION OF EXISTING ESTIMATES AND FIELD MEASUREMENTS OF AQUIFER PARAMETERS IN CACHE VALLEY, UTAH AND IDAHO


INKENBRANDT, Paul and LACHMAR, Thomas E., Geology, Utah State University, 4505 Old Main Hill, Logan, UT 84322-4505, huttonismyhero@hotmail.com

Attempts to simulate ground water conditions in Cache Valley have met with limited success. One of the limitations has been the paucity of reliable data on the hydraulic parameters of the various aquifers underlying the valley. In this investigation, aquifer parameters were compiled from existing but largely unpublished data, from specific capacity data reported in well drillers' records, and from aquifer tests conducted for this study. A GIS database was also created to organize this information.

A complete and thorough literature review was performed, which included obtaining unpublished aquifer test data from state and federal agencies, as well as reviewing Drinking Water Source Protection plans for each municipality in the valley. Specific capacity data from well drillers' records obtained from the Utah Division of Water Rights website, as well as the aquifer(s) each well is screened into, were entered into the GIS database, as were the transmissivity values estimated from the specific capacity data.

Five pumping tests were also performed. Drawdown data collected for each test provided clues regarding the surrounding geology, including the possible existence of a low permeability barrier and the presence of fractured material. Four of the tests were single-well tests using private domestic wells, and one was a multiple-well test using high-yield municipal wells owned and operated by the City of Logan. The transmissivity and storativity of the principal aquifer, into which the Logan City wells are screened, have been estimated to be 300,000 square feet per day and 0.00043, respectively.

The GIS database shows that the principal aquifer underlies the east side of the valley between Smithfield and Hyrum, and has the highest density of wells, most of which are screened into confined unconsolidated gravels. The transmissivity is highest in the principal aquifer and decreases to the west, north and south of it.