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

I
I
I
I
I
I
I
II
I
I
I
I
I
I
I
I
I
I
I

CL1695

The NRC report (pages 125 and 126) provides some insight as to the sources of water in

the Closed Basin where relatively high dissolved solids content is found, The conductance (a

measure of the total dissolved solids) of water in streams entering from the north (Crestone to

Sand Creek) is one-half to one-sixth of the streams entering the San Luis Valley floor from the

west (Kerber to La Garita Creek), Irrigation system drains that reached San Luis Lake probably

contributed high conductivity water to the Closed Basin, Shallow wells in the vicinity of San

Luis and Head Lakes in Townships 40 and 41 North, Range 11 East, are reported to have high

concentrations of dissolved solids (NRC, page 126), Calcium is reported to be the principal

positive ion in the northern streams, and sodium coming from irrigation drains and western

streams, High IDS and sodium concentrations are also found along the valley trough,

Characteristics of the Closed Basin Aquifer That May Impact on Yields

The NRC report contains descriptors of the characteristics of the shallow, unconfined

aquifer that provide some insight into the current production problems (pages 56 and 57),

Examples of the characteristics of the shallow aquifer in the Closed Basin as taken from the NRC

report are as follows:

1, that yields from shallow wells vary widely depending upon the nature of the
sediments in the valley fill;

2, that virtually all attempts to develop irrigation wells in the Closed Basin have failed,
because of the inability of the shallow valley-fill to yield water readily;

3, that higher well-yields are obtained from the shallow aquifer at locations in the
vicinity of Russel Lakes (35 miles north and west of Alamosa) and at locations in
several sections 6 miles northeast of Alamosa (see Figure 1, as both area are outside
the Project boundary); and

4, that none of the shallow ground water in the Closed Basin moves out of the area, and
that the water entering the Basin is lost to evapo-transpiration,

II