WSP00392

• File Number: 8276.150
• Description: Grand Valley Unit-Colorado River Basin Salinity Control Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/1/1992
• Title: 1991 Annual Report: Grand Valley Salinity Control Project Monitoring and Evaluation Program
• Water Supply Pro - Doc Type: Annual Report

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Of the 23 sites monitored, one had a microspray system, two had
sideroll sprinkler systems and 20 had surface irrigation systems.
The irrigation system at each site is identified in Table 2. At
each field with a surface irrigation system, automated electronic
flow recorders were installed to measure the volume of inflow and
outflow. These flow recorders were connected to electronic data
recorders. The recorders measured inflow and outflow every 10 or
30 minutes. The measured flow data was recorded and stored in the
data recorders.

At sideroll sprinkler or microspray irrigation system sites, the
volume of inflow was obtained from in-line mechanical flow meters
located on the sites. There was no surface runoff and the volume
of outflow was therefore not measured. For these sites, outflow
values were considered to be evaporation losses (Table 2).

The two radio telemetry weather stations located on the east and
west ends of the Grand Valley measured the climatic parameters
needed to calculate potential evapotranspiration (ETp). The
weather data for calculations of ET data were transmitted directly
to the Grand Junction field office every 15 to 20 minutes from the
two weather stations. These data were stored in the computer for
later use.

Crop consumptive use for each crop was determined using the
Modified Penman equation developed by Agricultural Research Service
(ARS), Fort Collins, Colorado. The crop coefficient curves for ET
calculations were developed by the SCS, ARS and the Cooperative
Extension office located in Grand Junction.

2. summary ot stream Gauging Data

No stream gauging data was collected by the SCS. The U.S.
Geological Survey (USGS) is responsible for collecting stream data.
In future annual reports, USGS data on flows and TDS will be
provided.

3. Irrigation Monitoring And Evaluation

a. summary of The Monitoring site Data

Approximately 350 acres were monitored in 1991. This acreage
accounts for only a very small portion (less than 1%) of the total
acreage in the Grand Valley. Refer to Appendix B for information
on Mesa county agricultural acreage. The average monitored site
was 15 acres. The 23 monitored sites were established in seven
different soil types, eight different irrigation systems and six
different crops. Crops monitored included alfalfa, corn, fall
grain, grapes and orchard.

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