WSP07375

• File Number: 8210.140.20
• Description: Colorado River Basin Organizations and Entities - Colorado River Basin States Forum - California
• State: CA
• Basin: Western Slope
• Date: 7/2/2003
• Author: Robert W Johnson
• Title: Part 417 Determinations and Recommendations Imperial Irrigation District Calendar Year 2003
• Water Supply Pro - Doc Type: Report/Study

3385
GROSS EFFICIENCY
(GROSS NET USE/ADJUSTED GROSS INFLOW)
80%
15%
70./~ ~
~ I
r, i , ~
i:)65"ii ^'
.
z i f
w I
u I .
" I l
u.. 60%
w
0
~ (
0
:5 55% i I
I
I 'I, I i
50"1. J
, ~ ~
45% ~ ~ ~ "
. .
i \ , r
~ . , '~!
. ~ "
40";'
~ . ~ ~ ~ ~ . ~ N ~ . ~ ; , ~ . 0 i
~ ~ ; ; ; . . . . . ~ . 0 0
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ . 0 0
N N
CALENDAR YEARS

Figure 5.

Gross Efficiency, shows the gross net use divided by the adjusted
gross inflow. (Source: Redlinger, July 2003),

The data presented in Figures 4 and 5 show that lID has historically been able to achieve
higher levels of efficiency than has occurred recently. If the efficiencies of the 1985-87
period been applied to the 2002 calendar year, the 2002 diversions would have been
reduced by approximately 256,000 acre-feet.

Technical Considerations

In evaluating operating efficiency Reclamation did not rely SOlely upon the denvative
calculations discussed ahove. Instead. Reclamation independently examined the
estimates provided by the experts for liD. CVWD, and MWD for water use for the three
components that make up efficiency calculatiolls - crop ET (ET,). leaching, and some
frnclion of tailwater. The following sections address and summarize the key points 111 the
materials reviewed, and the analyses perfonlled as part of the determinalion relating to
these components of operating efficiencies,

Crop ET

Crop ET is the sum of evaporation from the soil and transpiration from the crop Ihat is an
unavoidable consumption of water when growing crops. Key inputs to calcuiJllOn of

July 2, 2003

34

Detemlinations and Recommendation;
For lID - Calendar Year 2003