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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The State of Colorado has been atterrpting to make its Rio
Grande Conpact deliveries to the d=stream States on a
daily basis. The transmission of the larger flCMS through
the present deteriorated channels of restricted capacity
has resulted in large overflo.vs throughout the flood plains
of the Rio Grande, the Conejos River and the San Antonio
River with the resultant high, nonbeneficial transmission
losses. The overflow in the Rio Grande flood plain has
also restricted the discharge of the smaller tributaries
and drains, causing additional overflCM and loss of water.
Such diminution of the rreager water supply is not a local
problem as it adversely affects all of the water users in
the Upper Rio Grande Basin....

The Colorado Water Conservation Poard and the Bureau of
Reclamation have jointly made a preliminary evaluation of the
econanic feasibility of restoring the channels of the Rio
Grande and its tributaries in Colorado. This evaluation
consisted of deriving preliminary estillates of oonstruction
costs for restoring the stream channels; estillating the
annual cperation, maintenance, and replacement costs;
estimating the potential savings of water and the basin-
wide benefits resulting therefrom; deriving preliminary
benefit-oost ratios; and determining the expenditures
required for !lOre detailed studies of feasibility grade
investigations....

In restoring the channels of the main river and tributaries,
the present riverbed elevations would be retained to confonn
with the elevation requireITents of the present irrigation
systems. The river channels would not be deepened because
they could then act as major drains, thus disturbing the
hydrologic balance of the practice of subirrigation in the
valley. " .!I

The reduction in water losses that would result frOll
channel restoration was estimated frOll the results of
past investigations of rates of evapotranspiration in
the San Luis Valley and extensive studies of reducing
water losses in the Rio Grande Basin above Fort Quitman.
The value of water savings to the basin was kept conserva-
tively lCM at $60 per acre-foot. This is an average
value of water for irrigation in the Upper Rio Grande
Basin derived in other Bureau of Reclamation eoonomic
studies. . . .

.!I Underlining added

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