WSP01923

• File Number: 8054
• Description: Water Salvage
• State: CO
• Basin: Statewide
• Date: 1/22/1992
• Author: CWCB
• Title: Analysis of Water Salvage Issues in Colorado and Appendix-Irrigation Salvage - An Analysis of Water Salvage Issues in Colorado
• Water Supply Pro - Doc Type: Report/Study

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evaporation, evapotranspiration, or deep percolation to non-tributary aquifers. Likewise,
the term "saved water" will be used to describe the larger increment of water produced by
changes to historical diversion rates made possible with efficiency improvements.

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C. Methods of Improving Irrigation Efficiency

An accepted measure of overall irrigation efficiency is the ratio of crop consumptive use
to gross headgate diversions. This efficiency can be improved by either reducing diversions
or increasing crop consumptive use (or by a combination of both). Generally, the expanded
use doctrine limits adding new consumptive uses to a decreed Colorado water right. In
some circumstances, such as when an irrigator who historically has never had enough water
to satisfy his crop needs becomes able to get more water to his existing acreage, increased
consumptive use is allowed. Efficiency changes considered herein will focus on the more
common means of increasing irrigation efficiency - reducing losses thereby reducing the
diversion side. of the efficiency ratio.

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Often, an increase in efficiency is endorsed as a reduction in "waste" without an attempt
to define the term "waste". As already shown, non-consumptive losses generate return flows
which are used by others and such water is not necessarily wasted. While frequently an
increase in irrigation efficiency is promoted as conserving water supplies and in the public
interest, such generalities fail to recognize the intricate movement of water within an
irrigated region. Further, it is tempting to classify conveyance losses as non-beneficial uses
of water, but, in fact, such water actually serves the necessary and beneficial purpose of
moving the remaining water to its place of need. It is only when the method of conveyance
is not "reasonable and appropriate under reasonably efficient practices" that these losses
should be characterized as "non-beneficial." Section 37-92-193(4), C.R.S.

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What "reasonably efficient practices" means is central to statements about the efficiency
and waste involved in irrigation water use. A common understanding is that beneficial use
is a flexible concept which tolerates whatever degree of "inefficiency" is present in the
prevailing irrigation methods of an area. Courts will likely be reluctant to require
innovations with private investment that force any advance beyond those prevailing methods.
Likewise, the State Engineer can probably not require state-of-the-art irrigation systems in
an effort to reduce irrigation water diversions. However, the legislature, as the best arbiter
of public perceptions and desires, may be in better position to balance policy questions and
decide to move water users towards more efficient practices. It can do so by providing
incentives (funding or creating a marketable right as proposed in the salvage bills) or by
regulating (i.e., by declaring which "reasonably efficient practices" are necessary or otherwise
tightening the definition of beneficial use). Similar approaches have already been applied
to municipal users, i.e., financial and technical assistance on the one hand and mandatory
plumbing code revisions containing maximum fixture demands on the other.

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Absent regulation, current conditions give some incentives for irrigators to make
improvements to their systems. Some of the reasons cited by irrigators who have made

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