WSP01564

• File Number: 8273.600
• Description: Colorado River Basin Salinity Control - Federal Agency Reports - USDA
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1991
• Title: Colorado SCS Salinity Projects - Part 1 of 3 - General info and The Grand Valley Project
• Water Supply Pro - Doc Type: Report/Study

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underground pipeline. Water del ivered to the ifield is distributed to
the field through different irrigation system~.

The irrigation systems commonly used by farmers include: earth ditch
to siphon tubes, concrete ditch to gated pipe, ported concrete ditch,
underground pipeline to gated pipe as well as various kinds of
sprinkler systems_ These may be drip, microspray, solid set sprinkler
or sideroll sprinkler.

b. Monitoring Site Description

Overview: The initial goal was to monitor 35 sites annually as
outlined in the 1983 Grand Valley Monitoring and Evaluation Plan.
Since then, It has been decided that at least 16 acti,ve monitoring
sites would be maintained each ye~r. A total of 35 sites could be
monitored over the I ife of the M&E: program by maintaining 16 to 20
operating sites each year and rot~ting the equipment to new fields
after three to five years of irrigation monitoring_ Only a certain
number of sites can be maintained each year because of limited
equipment. Equipment cost for a monitoring site with one outlet and
an inlet runs from $5,000 to $6,000. This is a one-time capital cost
and not a repeating annual cost. Annual expenditures include nominal
operation and maintenance costs.

On-farm irrigation monitoring started in 1984 with the installation of
12 monitoring sites. Since then a minimum of 16 sites have been
maintained each year. Table 1 provides information on status of the
var'ious sites establ ished since 1985. Of the 16 original sites
installed in 1985, at least six were sti II being monitored through
1991 (Table 1). The remaining ten sites have been dropped because of
various problems with maintenance and operations.

Irrigation monitoring sites were establ ished to represent the general
conditions In the Grand Valley with regard to crops,soi Is, irrigation
system and management practices. Criteria establ ished for site
selection include: sites be isolated from other fields, i.e. water
source for inflow must be independent and tailwater from outflow must
be Isolated so that water from other sources do not get mixed. A
monitoring site is defined as a single field or a fixed portion of a
field, that is irrigated as a single irrigation set or a series of
sets. A site has a fixed size throughout the irrigation season.

Daily evapotranspiration (ET) data obtained from the two SCS weather
stations was made avai lable to two local television and radio stations
dai Iy, Monday through Friday. Weekly ET data was provided to two
local newspapers and Colorado State University Extension at Grand
Junction and Delta for their code-a-phone service for local producers.

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