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Download A Few Observations on Ground Water in Devils Postpile National Monument
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A Few Observations on Ground Water in Devils Postpile National Monument Chris Farrar U.S. Geological Survey y Ca Long Valle Dry Creek ldera Mammoth Mtn MCWD San Joaquin Ridge Wells Devils Postpile Dry Creek Geology from Snow Making Wells Bailey 1989 Devils Postpile Volcanic Rocks are the principal groundwater reservoir Mammoth Mtn MCWD Qal & pumice Glacial Basalt, Andesite, & Dacite Bishop Tuff Granitic Basement Not to Scale Thin, Discontinuous, Unconsolidated, Porous GW SW Extensive, Laterally Continuous, Consolidated with Fracture Permeability. Principal Aquifers. GW Mostly SW Two Distinct Members, Welded & Unwelded Zones. Thermal Water. Minor Aquifer Potential Fracture Permeability, Limited GW Storage and Flow Ground-Water Conditions and Connections • Qal, Qp, & Qg: Support Meadows, Wetlands, and Fens Vulnerable to Climate Change and Local Pumping • Volcanic Rocks: Main Source of Water to Wells and Springs Connections to External GW Basins Water Quality Issues – As, Fe, Mn, Thermal-water Ground-Water Vulnerabilities • Unconsolidated Aquifers: Climate Change – Change seasonal hydrograph Change in recharge & ET Local Water-Use: Probably minor & manageable Changes in GW—SW relations • Volcanic Rock Aquifers: Climate Change – Probably less significant to R & ET External Basin Water-Use – effects unlikely but possible Springs have greatest vulnerability Changes in GW—SW possible but localized • Water Quality: Mixing thermal and non-thermal, Ski-area pollutants Hydrologic Assessment Monitor Inventory Hydrogeology Develop Hydrologic Budget and Monitor for Changes and Trends Preserve, Protect, and Wise Frugal Use Inventory • Existing Data • Springs – Flow, temperature, chemistry • Tributary Streams – flow durations, sources • Wells – GWLs, temperature logs, litho. data Monitoring Needs • Piezometers: near streams, meadows, and fens • Springs: Flow, temperature, and chemistry • San Joaquin River: Establish Stage-discharge • Water-use: accounting and Ground-Water levels • Micromet being done now Questions ? Comments?
