STUDY NUMBER ; 10.3 



ORGANIZATION ; University of Montana (UM) 



TITLE OF STUDY ; Groundwater Use and Management: A Sole 

 Source Aquifer Study, Missoula Valley, Montana 



CONTACT ; William Woessner - UM Geology Department, Missoula 

 - 243-2341 



OBJECTIVE ; Evaluate the long-term quantity, quality and 

 availability of the natural groundwater system in the 

 Missoula Valley; begin a long-term monitoring program and 

 develop a predictive tool to evaluate the consequences of 

 current and future groundwater management practices. 



DURATION ; 1985 - 1987 



CURRENT STATUS ; In the summer of 1983, the City of Mis- 

 soula's Rattlesnake Creek water supply system was closed 

 because of giardia contamination. The city now relies solely 

 on groundwater for their drinking water. Approximately 7.6 

 billion gallons of water are withdrawn annually from the 

 underlying aquifer. 



The Missoula Valley Aquifer is directly connected to the 

 land surface with only sporadic layers of silt and clay to 

 protect it from downward infiltrating pollution. Improperly 

 installed septic tanks and the "French Drain" system of 

 stormwater disposal utilized by the City of Missoula are 

 major sources on contamination to the aquifer. 



This study is monitoring withdrawals from and discharges 



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