WSP05903

• File Number: 8583
• Description: Rio Grande Decision Support System
• State: CO
• Basin: Rio Grande
• Water Division: 3
• Date: 2/1/1998
• Author: Dr. John W. Hernande
• Title: Evaluation Of Salvage Well Production Problems In The Closed Basin Of The San Luis Valley Colorado
• Water Supply Pro - Doc Type: Report/Study

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001686

The Proposed Use of Open Drains

The NRC report also describes large "sump areas" in the Closed Basin and discusses a

proposed project to construct a trunk-drain to collect water from the sump areas and to discharge

them into the Rio Grande near the Lobatos gauging station, A description of the proposed open

drain projects is as follows (the Federal Emergency Administration of Public Works, 1935 as

taken from the NRC report, page 123 and 124):

"the drain would follow closely the trough of the basin, It would drain the
numerous shallow lakes which collect there during the wet season and serve to
lower the water table as much as 5 feet adjacent to the drain and stream channel.
This would permit the flow of many of the streams now seeping the area to be
carried to the sump as surface flow, and eliminate the present seeped conditions
, , " responsible for the losses by evaporation and transpiration, """ The drain
would cross the closed basin barrier in a deep ,cut and join [the] Rio Grande at
Hanson's Bluff, , , " The extent to which this supply can be [taken] by
construction of sump drains depends upon the depth of the drain and lateral
system, if any, and its general effectiveness in lowering the water table, This
remains at this juncture more or less a matter of conjecture,"

Volume of Salvage Water Available

The NRC report suggests that the amount, and sources of recoverable drainage, are much

more limited than some of the estimates of annual salvage yields that had been made prior to

1937, Estimates of the amount of water that could be salvaged by sump drains and added to the

flow of the Rio Grande were developed in a number offeasibility studies made between 1915

and 1935, These estimates run from 40,000 to 300,000 acre-feet per year (NRC, page 123),

The Closed Basin is described as having conditions that are conducive to water losses

through evaporation and transpiration by native grasses and brush (NRC, pages 121-124), The

sections of the NRC report on consumptive use by non-beneficial vegetation provide an estimate

(for 1936) of340,000 acre-feet of water losses from an area that was just over 400,000 acres in

the San Luis Closed Basin (NRC, Table 1, page 121), The areas of vegetation in 1936 were

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