11 Bonneville Basin: Geology of Pleistocene and Holocene Lakes

Tuesday, 5 May 2020
8:15 AM - 12:00 PM
Cascades C

MAPPING GROUNDWATER CONDITIONS AROUND GREAT SALT LAKE

Paper number: 11-4
Program: Theme Sessions
Time: 9:00 AM – 9:20 AM

Authors

Abstract

Great Salt Lake (GSL) and its adjoining wetlands are located at the lowest elevation of the regional GSL watershed. As such, GSL must be a sink for surface water as well as groundwater from a large area. Despite its potential as a regional groundwater discharge area, previous investigations of groundwater contributions to the entire GSL are limited. The goal of this project is to provide a comprehensive geodatabase of potentiometric surfaces and chemistry of groundwater adjoining GSL. We compiled groundwater level and chemistry data from publicly available databases, technical reports, and peer reviewed journal articles. Additional new samples and water levels were collected and added to the database. The compiled data were used to create maps of total dissolved solids concentrations, as well as a map of the potentiometric surface around the lake. Variations in water type and total dissolved solids are likely controlled by relative amounts of recharge and water-rock interaction surrounding GSL. A comparison of existing wetland water chemistry to groundwater chemistry shows local correlation and may provide evidence for groundwater contributions to some wetlands on GSL margins. Groundwater elevation controls the rate and direction of groundwater movement towards GSL. To better constrain groundwater elevations near the lake we compiled existing water-level data from a variety of sources including USGS NWIS data, state water-level data from previous reports and drillers logs, and a select series of new water-level measurements. This dataset was then used to create a potentiometric surface for groundwater surrounding GSL. Based on this potentiometric surface, a simple Darcy flux estimate of groundwater discharge to the lake bed was made. All of the data gathered by this study are provided in a single interconnected ArcGIS geodatabase. These data provide important baseline geochemistry and water levels for the groundwater system that can be used in a variety of future studies relating to GSL and its wetlands. This dataset and related future studies will provide an improved understanding of GSL’s groundwater system.

Geological Society of America Abstracts with Programs. Vol. 52, No. 3

doi: 10.1130/abs/2020RM-346561

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