WSP06833

• File Number: 8276.855
• Description: Grand Valley Unit - Colorado River Basin Salinity Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1974
• Title: The Grand Valley - Control of Salinity in Irrigation Return Flows
• Water Supply Pro - Doc Type: Publication

THE =~L T ~FtaDLEm

Economic losses attributed to salinity in the United
States amount to about $16 million annually. The salt
problem results from:

. Inefficient irrigation-In the Grand Valley farm
irrigation efficiencies range between 30 and 40
percent (about 60 to 70 percent of diverted water is
110t useu for crop production). The greatest loss of
water is from surface runoff, with undetermined
amounts returning to the river via deep percolation
and ground-water movement. About 8-9 feet of water
are diverted for each acre of cropland, more than
double the amount required for optimum crop
production.

. Shallow water tables and saline soils-Low irrigation
efficiency results in rising water tables.
Evapotranspiration of water from the shallow ground
water deposits salt in the soil. Canal leakage
contributes to increased water table height.

. Salt accumuJation- The Colorado River accumulates
about 600,000 tons of salt annually as it passes
through the Grand Valley. This is a significant part of
the salts that must be dealt with by subsequent users
of Colorado River water. Although it is not crear
what portion of this salt load can be attributed to
irrigation, the total accumulation is equivalent to
about 9 tons of salt per year from each irrigated acre
in the valley.

9t6Z.JO

SelUFlCES

A verage Sa It Load
June 1965 - May 1966

Natural Point Sources
and Wells
(2430 tons per day)

Municipal
and
Industrial
(357 tons per day)

elF

S~LT

Average Salt Load
November 1963 - October 1964

Net Runoff
(610 tons per day)

Municipal
and
Industrial (less than 1%)
(64 tons per day)

Irrigated Agriculture
(1180 tons per day)

Upper Colorado
River Basin Inflow
72%
(9833 tons per day)