Title

Stalking Water: Using Water Geochemistry to Track Groundwater History

Presenter Information

James Patterson

Document Type

Oral Presentation

Location

SURC Ballroom C/D

Start Date

16-5-2013

End Date

16-5-2013

Abstract

The limited available surface water in the arid parts of the Northwest has placed an ever increasing demand on the local groundwater. In the Upper Kittitas County (west of Thorp to Snoqualmie Pass) all of the surface water has long since been allocated; as the headwaters for the Yakima basin, most of this water is used to sustain the multi-million dollar agricultural industry of the basin. Therefore, the burden of population growth depends on the sustainable use of groundwater, a resource that is now being regulated for domestic use. Unlike many groundwater reservoirs, which are located in unconsolidated sediments, the subsurface in the Upper County is composed mostly of fractured bedrock. Thus, water does not flow through pores in the sediment, but instead flows mostly through fractures in the various types of hard bedrock. This complex geology makes identifying aquifer size difficult by conventional methods, but creates a unique opportunity to use and develop geochemical techniques to answer the ever-present questions. In this study, water samples were collected from multiple aquifers and analyzed for trace element concentration using the Inductively Coupled Plasma–Mass Spectrometer (ICP-MS) in the Geology Department at CWU; with this data, the geochemical fingerprint of each aquifer becomes apparent. Mixing between aquifers can also be traced. This information about where groundwater obtains its geochemical signature and which groundwaters are connected is a crucial part of the answer to the question of how to develop this resource sustainably; a crucial part that cannot be determined without geochemical techniques.

Poster Number

59

Faculty Mentor(s)

Carey Gazis

Additional Mentoring Department

Geological Sciences

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May 16th, 8:20 AM May 16th, 10:50 AM

Stalking Water: Using Water Geochemistry to Track Groundwater History

SURC Ballroom C/D

The limited available surface water in the arid parts of the Northwest has placed an ever increasing demand on the local groundwater. In the Upper Kittitas County (west of Thorp to Snoqualmie Pass) all of the surface water has long since been allocated; as the headwaters for the Yakima basin, most of this water is used to sustain the multi-million dollar agricultural industry of the basin. Therefore, the burden of population growth depends on the sustainable use of groundwater, a resource that is now being regulated for domestic use. Unlike many groundwater reservoirs, which are located in unconsolidated sediments, the subsurface in the Upper County is composed mostly of fractured bedrock. Thus, water does not flow through pores in the sediment, but instead flows mostly through fractures in the various types of hard bedrock. This complex geology makes identifying aquifer size difficult by conventional methods, but creates a unique opportunity to use and develop geochemical techniques to answer the ever-present questions. In this study, water samples were collected from multiple aquifers and analyzed for trace element concentration using the Inductively Coupled Plasma–Mass Spectrometer (ICP-MS) in the Geology Department at CWU; with this data, the geochemical fingerprint of each aquifer becomes apparent. Mixing between aquifers can also be traced. This information about where groundwater obtains its geochemical signature and which groundwaters are connected is a crucial part of the answer to the question of how to develop this resource sustainably; a crucial part that cannot be determined without geochemical techniques.