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<br />Introduction 11
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<br />resource development in the Upper Basin
<br />and resulting slowing of economic growth.
<br />Another and mOre important factor is the
<br />heavy Colorado River runoff beginning in
<br />1983 which purged significant amounts of
<br />salt from the reservoirs and further
<br />reduced salinity through dilution. This
<br />salinity improvement, while not permanent,
<br />is expected to persist for several years.
<br />
<br />. Since 1976, greater attention has been
<br />given to the blending of Colorado River
<br />water with other waters to achieve more
<br />desirable salinity levels for M&I uses
<br />(notably in the Metropolitan Water Dis-
<br />trict of Southern California [MWD] service
<br />area) and to reclamation of wastewater for
<br />reuse in industry, landscape irrigation, or
<br />in groundwater recharge. Currently, the
<br />extent of blended water supplies also is sub-
<br />ject to the cost of power for pumping.
<br />The economic impacts of various salinity
<br />levels on the costs of blending water or
<br />treating it for reuse have not been dealt
<br />with to the desired degree in the earlier
<br />research.
<br />
<br />For all these reasons, it appeared timely to
<br />update and supplement the data appearing in
<br />the Kleinman and Brown report so that credible
<br />and defensible estimates of current and future
<br />benefits of salinity control can be developed,
<br />with as much accuracy as the data permit. By
<br />developing a flexible, yet manageable computer
<br />I,rogram (a program suitable for use in an IBM-
<br />compatible personal computer adequate for
<br />computer graphics), future estimates of thc eco-
<br />nomic impacts of salinity control can be done
<br />easily and swiftly. The program will permit
<br />ready modification of input parameters, e.g.,
<br />salinity (TDS) levels, changes in crop values and
<br />in agricultural acreage planted. Moreover, shifts
<br />in water use from agriculture to M&I; changes
<br />in damage threshold levels; shifts in location of
<br />use that will occur as the Central Arizona
<br />Project matures and population changes; chan-
<br />gcs in discount rate; changes in costs of applian-
<br />ces, treatment processes, etc., all can be
<br />accounted for in the program.
<br />
<br />The Rationale for Defining
<br />Salinity Damages
<br />
<br />Earlier attempts to measure the effects of
<br />salinity have treated such effects as absolute.
<br />That is, the physical effects of salinity levels in
<br />reducing crop yields, in corroding and thus
<br />reducing the useful life of water-using household
<br />devices, etc., have been measured against an
<br />"ideal" salinity level at which no physical effect
<br />is apparent. Then these physical effects are
<br />described in economic terms, such as the value
<br />of reduced crop production and the monetary
<br />costs of more frequent replacement of washing
<br />machines, household piping, etc. Such an
<br />approach can be misleading.
<br />
<br />This measurement of physical and economic
<br />effects of salinity in water supply against an ideal
<br />water supply appears to have been taken with
<br />little justification. It may reflect merely the
<br />researchers' belief or assumption that saline
<br />water has deleterious effects which logically
<br />should be measured against a standard of pris-
<br />tine water whose salinity level is below the
<br />threshold that causes measurable effects.
<br />However, such pristine water is not always found
<br />in nature and certainly is rarely found in waters
<br />that have been subjected to the impacts of
<br />human activity.
<br />
<br />Salinity Effects vs. Salinity
<br />Damages
<br />
<br />There is a fundamental question underlying
<br />this study, a question whose answer has a major
<br />influence on the study findings, yet one that can-
<br />not be answered solely through engineering or
<br />economic analysis. That is, which physical and
<br />economic effects of saline water should be
<br />termed "damages"? The answer is not provided
<br />from engineering, economics, chemistry or biol-
<br />ogy. There are philosophic aspects to consider.
<br />For example, the term "damage" carries with it
<br />the concept of mitigation. Rationality leads us
<br />to take steps to reduce or otherwise correct
<br />damages, particularly those which are caused by
<br />man's action or inaction, and which can be con-
<br />trolled or corrected at a cost that is less than the
<br />resulting benefit. Yet, merely because water is
<br />saline, it is not always appropriate to consider it
<br />as a source of damage.
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<br />31
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