WSP05094

• File Number: 8277.600.10
• Description: Big Sandy River Unit - Colorado River Salinity Control Program
• State: WY
• Basin: Colorado Mainstem
• Date: 2/1/1988
• Title: U.S.D.A. Selected Plan - Big Sandy River Unit
• Water Supply Pro - Doc Type: Definite Plan Report

.L

TABLE 2-1

HISTORIC EVALUATION VS. PRESENT CONDITION

~

Colorado River Basin Salinity Control Project
Big Sandy River Unit - Wyoming

Historic
(1960-1977)

Present
(1986)

10...-':

Irri!,ated Acres

18,370
14, 320!.l

18,370

Water-Righted Acres

15,700

Onfarm Efficiency (Percent)

35

82
393/

Conveyance Efficiency (Percent)

82

Salt Load from Irrigation (Tons/Year)

29
149, 180~J
133,86~/

32
157,5703.1
142,2502/

-~ ,~

Project Efficiency (Percent)

Annual Salt Load (Tons/Year)

'.~:

1/ Average irrigated acreage from a low of 11,485 acres in 1961 to a high of 15,700 acres in
1976.

~~,

~/ The 4 percent increase of onfarm irrigation efficiency results from diverting a given
average annual water supply of 57,620 acre-feet to 15,700 irrigated acres (present)
instead of 14,320 irrigated acres (historic).

l/ Under present condition, the system is assumed to be in balance (no loss to ground
water); therefore, outflow will increase from the historic outflow of 29,580 ac ft to
present outflow of 31,430 ac ft. This increased outflow increases salt loadings to the
river by 8,390 tons/year.

~/ Average va1ue for 18-year eva1uation.

'~
;~

;0:' ~

15,320 tons to 32,720 tons is a result of lowering the water table,
allowing the natural interaction of the river and the aquifer flow to
occur.

(;-11 ~. "
v ,I ..i";

2-4

~