WSPC04137

• File Number: 8272
• Description: Colorado River - Colorado River Basin Salinity Control Program - CRBSCP
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 2/1/1995
• Author: Aneth
• Title: Geochemical Progress - Navajo Sandstone in Water Canyon Narrows - Utah - Aneth Progress Report
• Water Supply Pro - Doc Type: Report/Study

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IODIDE MIXING MODEL CONSTRUCTED

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Mixing hnes between the three saJme end-member waters wilh the end-member waler from the Navajo aquifer
(chloride concentrations less (han or equal 10 60 mgIL) were constructed using the equation:

Cmix=CI'Y+C2'(I-Y), (2)

where Cmix is the iodide or chloride concentration of the end-member mixlure. eland C2 are the iodide or
chloride concentrations of the end-member water, and V is the volume fraction of the Navajo aquifer
end-member waler. Thirty-five water samples from the Navajo aquifer with chloride concentrations larger (han
60 mgIL were compared with the ralio shown on the constructed mixing lines (figure below). In water samples
from the Navajo aquifer. the iodide-Io-chloride weight ratio decreases wilh increasing chloride concentration,
generally following the end-member mix.ing lines constructed with the mean Upper Paleozoic aquifer
end-member water composition (figure below). If Ihe salinity source was OFB or comingJed injeclion water,
iodide-to-chloride ralio~ in water from the Navajo aquifer wells sbould follow tbe upper mix.ing lines as the
chloride concentration increases (figure below). This is nol the trend shown and is in agreement wilh the results
of the bromide-to-chlonde data and mixing model wbich indicates thai OFB or comingled injection Waler is not
the source of salinity.

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OOMINGLED WAlER MIX LINE

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OIL-FIELD ~RINE ~IX LINE _ -2
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UPPER PALEO-
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0.0
10 100 1,000 10,000 100,000
CHLORIDE OONCENTRA 1lON, IN MILLIGRAMS PER lIlER

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EXPLANATION
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