WSP02111

• File Number: 8273.600
• Description: Colorado River Basin Salinity Control - Federal Agencies - USDA
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 2/1/1992
• Author: USDA
• Title: DRAFT - Grand Valley Salinity Project Monitoring and Evaluation Program - 1991 Annual Report
• Water Supply Pro - Doc Type: Annual Report

w
o
C::l

,

....1

i{/: The 1991 irrigation monitoring, site data presented in,Table 2 as
Annual Summary indicate the following:

1. The average amount of water applied to the f,ield was 56.4 acre
inches per acre for the 23 sites. When separated by surface and
sprinkler systems, water app,lication was 58.3 acre inches for the
surface systems and 45.8 acre inches for the sprinkler systems.

2. Average water appl ication for different crops varied from a high of
67.1 inches per acre for a I fa I fa to a low of 39.8 acre inches ,for
grapes.

3. The actual evapotranspiraticn varied for different sites based on
crops, time of planting and harvest date. Table 2 shows the average
actual ET to be about 26.6 inches for the 23 sites. When broken down
by surface and' spri nk I er systems, actual ET was 26.5 and 31.1 i nC,hes
respectively.

4. The average deep percolation was about 16 inches f,or all 23 sites;'
16.5 inches for surface sites, and 7,1 inches for spr ink I ers. Deep
percolation for different crops varied considerably from 18.3 inches
for alfalfa to 6.8 inches for grapes. There is not much difference in
deep percolation between annuals and perennials; 16.4 inches versus
15.7 inches.

:.~:.: -;:~
::~;:;:5

5. The seasonal application efficiency ranged from a
fal I grain site to a high of 76% for an orchard site.
site was the only site without any deep percolation.
efficiency for all monitoring site was 45.4 percent.

low of 277. for a
This orchard
The average

6. Surface runoff from sites varied considerably ranging
4.1 inche,s to a high of 39,,5 inches. On the average, 15
water coming to the field was lost to surface runoff, or
t'otal water applied to the field.

f rom a
inches
267. of

low
of
the

of

b. Summary Of Field Evaluations

The foll'owing is a brief summary of, the 1991 monitoring field
evaluations:

1. Overuse of water is prevalent throughout the Grand Valley
because of abundant supply of inexpensive irrigation water.
Most producers are not concerned about irrigation water
management (IWM). Very few farmers practice a high degree of
IWM.

2. Poor irrigation efficiencies at some sites are due to over
irrigation, i.e. fields are irrigated too soon and too long.
All of the monitored surface irrigation systems are capable of
irrigating at 507. or greater efficiency with proper
management. 11