WSP05273

• File Number: 8210.470
• Description: Pacific Southwest Interagency Committee
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/30/1966
• Author: Unknown
• Title: Phreatophyte Symposium 66-3 Meeting - August 30 1966
• Water Supply Pro - Doc Type: Report/Study

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Desert Washes
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In the desert regions where stream courses consist of deep alluvial
desert washes, the surface flow is limited to flash floods that recharge
the ground-water reserves. The vegetation in these areas is usually
dominated by mesquite, which obtains its water from the deep alluvial
deposits. These groves of mesquite, which are so abundant in parts of
Arizona, undoubtedly use a fairly large amount of water from these
deeper sources which, in some cases, can be salvaged. Mesquite stands
have some values for wildlife, but they usually have a low recreational
value except in a few isolated spots near main roads or reservoirs.

Playas

In the great basin and other parts of the al-id Southwest, there are
numerouS interior drainage basins, of which the playa is the central
part. In many cases, the playas have water close enough to the surface
to be called wet playas, and typical phreatophytes such as pickleweed,
greasewood,~and rabbitbrush grow in a zonal arrangement from the edge
of the playa outwards. Large areas of greasewood have been included
in the reports of phreatophyte acreages in the United States. In some
cases, it is doubtful if the management of this vegetation could
contribute much in the way of water savings. The water is frequently
alkaline, and therefore cannot be used for irrigation or domestic uses.
Management of areas of this type would be indicated for the development
of grass stands for grazing of livestock. One possibility is to inter-
cept ground water upslope from the area of phreatophyte use by pumping
with wells for beneficial use of the water. Other uses, such as recrea-
tion and wildlife, are almost nonexistent in these playa edges. There
are, of course, areas where vegetation of this type may be growing close
to flowing streams or rivers so that the losses of fresh water would
indicate management to a less water-loving vegetation.

Summary

It is evident that the problems of land management vary a great deal
on phreatophyte and riparian lands. Basically, the approach in manage-
ment must be first to determine the best economic use. \.Je need to know
how much water is actually lost by the vegetation as it now exists, and
also be able to estimate the amount which might be saved by various
vegetation treatments. Then, if vegetation removal or management is
indicated from a water-salvage standpoint, methods of controlling the
various phreatophytes will have to be developed. Many of the species,
particularly tamarisk, are very difficult to control. They are aggres-
sive, rapidly invading moist areas; also the mature plants are quite
difficult to remove economically. In many cases, however, water savings
have been sufficiently great to justify the expense. The situation in
mountain vegetation is even more difficult because of the complexity of
the intermingled present and potential uses of such land.

And finally, if increased water is produced by land management, definite
problems of water rights begin to become apparent. It is around this
outline that we have developed our symposium program.

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