WSP07805

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 2/1/1984
• Title: Colorado River Water Quality Improvement Program - Meeker Dome Unit Colorado - Preliminary Findings Report - Feb 1984
• Water Supply Pro - Doc Type: Report/Study

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SUMMARY (Continued)

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Problem identification and quantification activities were directed
at determining the nature and volume of salt loading from Meeker Dome.
From data collected during the problem identification and quantification
activities, it was hypothesized that an insufficient plug and deteri-
orated casing in one of the wells allowed saline water to move verti-
cally into near surface aquifer( s) in the Morrison Formation. The
saline water moved laterally by gravity flow along the Morrison and
Dakota Formations and surfaced in springs and seeps where the Dakota is
exposed by the White River.

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To investigate the flow-mechanism hypothesis, a verification pro-
gram was initiated in 1980. The program included the installation of a
monitoring network and the cleaning, testing, and plugging of three of
the abandoned oil wells. After the last of the three oil wells had been
plugged, a significant reduction in ground water levels and flows of
springs occurred. Analysis of the monitoring data indicates that the
plugging operations conducted in the three wells impeded the hydraulic
connection that existed between the shallow and deep aquifers. Further-
more, the continuing decline in water levels in the observation wells
provides strong evidence that the well plugs are still intact. The
effect of well plugging is depicted on the following page.

The verification activities confirmed that deep exploratory oil
wella provided the corridors through which saline water under pressure
was escaping to surface formations and flowing into the White River.
The first year after completion of verification activities, salt load-
ing from the dome was reduced about 74 percent from preplugging levels,
with a total reduction of 15,800 tons. This salt loading reduction
represents a decrease in salinity of the Colorado River at Imperial Dam
of about 1.6 milligrams per liter (mg/L) at an annual cost of $149,000
per mg/L. The cost effectiveness of the Meeker Dome Unit is compared
with the Grand Valley and Lower Gunnison Basin Units in the table on
page S-4.

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Before the 1981 plugging of the three wells, the salt loading from
the area was estimated at 21,400 tons annually with a 2.2-mg/L effect at
Imperial Dam. After plugging, the salt loading was reduced to 5,600
tons per year or a salinity effect of 0.6 mg/L. The salinity reduction
value of 1.6 mg/L attributed to the Meeker Dome Unit is the difference
between the 2.2-mg/L prep lugging level and the O.6-mg/L postplugging
level. It is possible that had the 1981 plugging not been undertaken,
the salt loading from the dome would have eventually returned to the
pre-1968 condition when salt loading from the dome was estimated at
about 57,000 tons annually with a salinity effect of about 5.8 mg/L. If
the 1981 plugging proves totally effective and the annual salt loading
value becomes 0, then it could be argued that the combined effect of
both plugging efforts (1968 and 1981) could be 57,000 tons with a reduc-
tion in salinity at Imperial Dam of 5.8 mg/L.

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Costs of the Meeker Dome investigations were $2,870,000 through
fiscal year (FY) 1983. It is estimated that an additional $160,000 will
be needed to complete monitoring activities and a final report. The

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