WSP11421

• File Number: 8276.855
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1993
• Title: 1993 Report to the USDI-Bureau of Reclamation - Grand Valley Demonstration Project
• Water Supply Pro - Doc Type: Report/Study

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sixth irrigations and reduced furrow flow rates during the second irrigation.

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c) Data obtained from field M51 indicates the operator understands irrigation water
management as it pertains to this field,

Field M55 results show improved water management and reduced deep percolation
with the surge system.

Comparisons between fields that were full field monitored and fields that were
evaluated by single furrow measurements are desirable, but a limited number of
fields have total irrigation events available for comparison. Fields that lend
themselves to full field evaluations are difficult to find since few have isolated
inflows and outflows for accurate flow measurements.

SALT LOAD REDUCTION:

Salt load reduction estimates made from the 5 fields that were fully monitored by
the SCS monitoring team during the past four irrigation seasons are shown below.

Salt load reduction from selected fields.
(A) (B) (e) (0) (E) (F) (G) (H)
Acre Inch reduction
Surge Salt from Surge Tons
Farm Acres Tons/a. i. 1990 1991 1992 1993 Total (B)x(Clx(Gl

M11
MIS
M43
MSl
MS5

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The 197.4 tons of salt saved divided by the 43.5 acres indicates an average salt \" .v,,\ ,I
reduction of 4.5 tons per acre over the four year trial from these selected fields. (>'
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7.5
16.6
4.8
9.6
5.0

0.280
0.263
0.341
0.263
0.28

8.9
10
17.5

10.9
8.6
1.4
2.0

19.8
25.6
6.5
8.8
8.0
Total

41.6
111.8
10.6
22.2
11.2
197.4

7.0
-12.4
5.7 1.1
8.0

The cost of the surge equipment purchased under this agreement, used on these
five farms, was $6,557.00. This equipment is assigned a 15 year life under the
USDA portion of the Colorado River Salinity Control Program.

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This equipment cost of $6,557,00, amortized at 8% for the 15 year life of the \
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surge units, divided by 4.5 tons/per acre times 43.5 acres equals $3.91 per ton of./" ,'-
salt. ./"\ I '..'

The tons of salt per acre inch of deep percolation, shown in column C, is less than ':\'",.,
the weighted valley wide average of 0,337 tons per acre inch, shown in Table 1 / '//~:":

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