Columbia Basin GWMA
 Subsurface Geologic Mapping and Hydrogeologic Assessment Project Progress Report
Groundwater Geochemistry

Dimitri Vlassopoulos

SS Papadopulos and Associates
Portland, Oregon
Presented at GWMA Board Meeting, Othello, WA
January 22, 2009
  • Major ion chemistry
        • –Changes along flow path
        • –Relative age
        • –Recharge sources
        • –Mixing
  • Stable Isotopes
      • –Water sources (precipitation/runoff, surface water)
      • –Ancient (glacial) versus modern recharge
  • Atmospheric tracers (groundwater age-dating)
      • –Radiocarbon, tritium, CFCs, SF6
      • –Groundwater “age” (time since recharged)
      • –Mixing of old and young water (pumping effects)

GWMA Well Sampling 2008

GWMA Well Sampling 2008


Groundwater Geochemistry, Age and Recharge

Groundwater Geochemistry, Age and Recharge


Apparent Groundwater Age (Radiocarbon years)

Royal City

Wells #1, #2

  • Shallow-cased water supply wells completed in Wanapum
  • Static water levels steady
  • Mixture of older and “young” water (recharged  since 1950s)
  • Recharge from Frenchman Hills sufficient to sustain withdrawals

Royal City Well Sampling

Moses Lake

Well #18

  • Supply well completed in Wanapum (Frenchman Springs)
  • Static water levels stable
  • Mostly “young” water (post-1950’s)
  • Direct connection to East Low Canal  through Roza/Upper Frenchman Springs flow zones

 Moses Lake Well #18

Moses Lake 

Well #17

  • Supply well completed in upper Grande Ronde (Sentinel Bluffs)
  • Static water levels declining
  • Mixture of old and “young” water (average recharge age ~6,000 years)
  • Recharge from “young” water component (<20 %) is too small to offset withdrawals
  • Limited connection to surface recharge

 Moses Lake Well #17



Irrigation well 20 miles east of Moses Lake
  • Well completed in Lower Grande Ronde (Umtanum and Ortley)
  • Static water levels declining
  • Old water (recharge age >10,000 years)
  • No present-day surface recharge sources

Odessa Well

Horseshoe Bend


Irrigation Wells
  • Shallow (132’) well in use since 1948 (Roza/Alluvium)
  • Deeper (605’) well in basalt (Wanapum and uppermost Grande Ronde)
  • Static water levels stable
  • Predominantly young water in shallow well, predominantly older water in deeper well
  • Relatively low groundwater use area
  • Connection to surface recharge (Sprague Lake) sufficient to recharge shallow well





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Last Updated ( Wednesday, 18 March 2009 )