WSP00631

• File Number: 8272.900.30
• Description: Colorado River Basin Salinity Control Program - Indian Tribes
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 7/1/1993
• Title: Salinity Verification - Phase I Final Report for Navajo Nation Unit - San Juan county NM - Salinity Control Study
• Water Supply Pro - Doc Type: Report/Study

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An off-farm program to reduce seepage and associated salt loading by about two-

thirds would involve such practices as using pipe or concrete lining to repair

about 200 miles of the off-farm distribution system. The off-farm program would

reduce salt loading by about 10,000 tons. Program costs for off-farm improvement

of 200 miles of canals and laterals at $10 per installed foot of 12-18" concrete

pipe would be about $11 million. Average annual cost would be about $91 per ton

of salt load reduction.

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Table 5 -- Water and Salt Balance, Future With Project Conditions,
San Juan Salinity Control Study, Navajo Nation Unit (5,800 acres)

----WATER--
-AF /A- -AF /Yr-
DIVERSION 5.5 31,900
RETURN TO RIVER (Off-farm)
Canal Seepage 0.5 2,900
FARM DELIVERY 5.0 29,000
RETURN TO RIVER (Onfarm)
Ditch Seepage .0.3 1,700
FIELD DELIVERY 4.7 27,300
VEGETATIONAL USE
Crop Consumptive Use 2.5 14,500
Phreatophyte Use(lO%) 0.5 2,900
RETURN TO RIVER (Onfarm)
Surface 0.4 2,300
Deep Percolation 1.3 7,500
RETURN SUMMARY
Canal Seepage 0.5 2,900
Ditch Seepage 0.3 1,700
Surface 0.4 2,300
Deep Percolation 1.3 7,500
TOTAL 14,400

OFF-FARM SALT PICK UP (CANAL)
ONFARM SALT PICK UP
TOTAL SYSTEM SALT PICK UP (Returns less Diversion)

-------SALT-------
--EC-- --T/AF-- -T/yr--

0.52 0.45 14,400
2.40 2.10 6,100
0.52
2.40 2.10 ,'-{~.:<..
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0.52 ' ~g~~

0.52 0.45 1,000
2.40 2.10 15,700
2.40 2.10 6,100
2.40 2.10 3,700
0.52 0.45 1,000
2.40 2.10 15,700
26,500

4,800 TONS (0.8 T/A)
7,300 TONS (1.3 T/A)
12,100 TONS (2.1 T/A)

The difference between the salt pick up values shown in Tables 4 and 5 is
indicative of how project action might reduce salt pick up:

OFF-FARM
ONFARM
TOTAL

14,400 T
34,000 T
48,400 T

(0.8 T/A) -
(1. 3 T/A)
(2.1 T/A)

(2.5 T/A) - 4,800 T
(5.8 T/A) - 7,300 T
(8.3 T/A) - 12,100 T

16

. .

9,600 T (1.7 T/A)
26,700 T (4.5 T/A)
36,300 T (6.2 T/A)

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