WSP09197

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1981
• Author: USDOI
• Title: Quality of Water - Colorado River Basin - Progress Report No. 10 - January 1981 -- Part 2 of 2 -- Part X - page 99 through end
• Water Supply Pro - Doc Type: Report/Study

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SPECIAL STUDIES (continued)

E. Lower Colorado River Salinity Investigations

In February of 1970, the Water and Power Resources Service began a
trial program to analyze the source and makeup of the salt load arriving at
Imperial Dam on a daily basis. Conductivity measurements were made each
day at 10 stations between Parker Dam and Imperial Dam. The network
included essentially all significant diversiona, surface return flows and
major river stations.

An intensive program was carried on for 1 year. After 1 year of
operation, the frequency of sampling was reduced. During the fall of 1971,
an experimental program of automatic salinity monitoring ~as started.
Conductivity probes were installed at nine stations on the lower river and
the data transmitted by telemetry to the Boulder City and Imperial Dam
offices. The nine stations as listed below.

1.
2.
3.
4.
5.
6.
7.
8.
9.

Colorado River below Hoover Dam.
Colorado River Indian Reservation Main Canal near Parker.
Poston Wasteway near Poston.
Palo Verde Canal near Blythe.
Colorado River at Taylor Ferry near Cibola.
Colorado River below Cibola Valley.
Yuma Mesa Drain near Yuma.
Main Outlet Drain Extension Bifurcation for MODES 2 and 3.
Colorado River at the Northerly International Boundary ahove
Morelos Dam.

Recently the Intensive Salinity Surveillance Program was changed. As
of September 30, 1980 the water quality telemetering program was discon-
tinued but weekly samples are taken from the first six of the previously
mentioned stations. Daily conductivity measurements are taken at Imperial
Dam in conjunction with the requirements of meeting Minute 242. The
Geological Survey is now responsible for the continuous water quality
monitoring probes at Imperial Dam and on the Main Outlet Drain Extension
for both continued research and data gathering. There are plans to install
continuous monitoring probes at Hoover and Parker Dams and at Needles. The
installation at Needles will test three different probe systems to deter-
mine which best suits the needs of that and future sites.

In addition to the nine formerly telemetered stations, water quality
samples are collected from five other stations. Individual samples are
analyzed for conductivity. The Geological Survey Laboratory makes weekly
analyses for total dissolved solids (residue at 180. C) and monthly anal-
yses of the chemical constituents.

Sampling frequencies for all stations were selected from an analysis
of past records so that samples would represent the actual salt load
with an error of less than 5 percent, 95 percent of the time. The five
other stations and the selected frequencies are shown in the following
tabulation:

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