WSP07035

• File Number: 8509
• Description: San Luis Valley
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 12/1/1969
• Title: Irrigation Water Management Study of the San Luis Valley Colorado - PART 1 of 2
• Water Supply Pro - Doc Type: Report/Study

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This study did rot attenpt to detennine the practicability of a
drainage system for recovering water nON used by greasewood and
rabbitbrush. Rather, the study has attenI:>tec1 to present sane broad
facts concerning the extent of this vegetative type and certain
considerations which should be made before a drainage project of
this nature is undertaken. It is felt that nothing should be done
which might leave large areas of extrerrely erosive soil bare of
vegetative cover. 'Ibe danger of uncontrolled wind and water erosion
is too great. (By counties the acreage of chico land with a water
table at less than 10 feet depth is roughly: Saguache - 195,000;
Alarrosa - 195,000; Rio Grande, Canejos and Castilla- 20,000.)

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Cost of controlling chico on any extensive acreage has not been
definitely established. A report from Region 5 of the Bureau of
Reclamation 1/ shows an initial cost of $20 an acre for r=t plONing
salt cedar. -Arumal maintenance with aerial spraying costs about $4
an a=e. Initial control with aerial spraying of three pounds of
silvex costs $10 an acre. Brush cutters and rotary =ers averaged
$2.50 per a=e. Much of the chico land of the study area is sodium
saturated and extrerrely difficult to drain. Assuming that the land
can be drained and that this drainage will cost about $30 an acre,
the cost of water salvage approaches a no profit return relationship.
Presently, the rrost practical approach to this problem is a spraying,
seeding and irrproverrent program in selected areas to control the chi<Xl
and allON rrore beneficial vegetation in the way of grasses and forbs
to cane in. 'Ibis should be aC<Xlrrplished slONly on an experimental,
individual basis and can proceed with special projects under going
programs or be speeded up with additional incentive payments or
<Xlst-sharing.

OI'HER PHREA'IOPHYTES

About 91,000 acres of the San Luis Valley are in native hay or pasture.
Sane of this land supports mainly sedges and rushes because of the
high, uncontrolled water table. Though these poorer quality mea<'l=s
and pastures produce relatively small arrounts of forage, they are not
worthless. Sane of these wetlands support good, productive grasses.
Though good irrigation or efficient water use on this land is diffi-
cult or impossible, little expense is involved in its management.
Same fanners and ranchers feel that native hayland is the rrost
important part of their fann or ranch. If the water table is perma-
nently lONered to salvage irrigation water to be used downstream,
then it is felt that a large acreage of the land's natural forage
potential will be damaged. Production <Xluld be in=eased on much
of this land by surface drainage and replacing unproductive sedges
and rushes with good grasses and legmres and with i=igation wate r
management.

Y See reference 30

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