PROJ00518

• Contract/PO #: C153484
• Contractor Name: San Luis Valley Water Conservation District
• Contract Type: Grant
• Water District: 0
• County: Rio Grande
• Bill Number: FSG
• Loan Projects - Doc Type: Feasibility Study

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Table I-I
Wagon Wheel Gap Reservoir Characteristics

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Storage capacity (af).... ....... ............
Dam crest length (ft).......................
Dam height (ft above river level)...........
Top of dam - (ft above msl).................
Reservoir length (miles)....................
Drainage Area (sq mi).......................
Estimated Mean Annual Runoff (1948-85, af)..

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1,000,000
1,200
340
8,780
11.8
------- 751
------ 386,500

500,000
975
260
8,700
9.8

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A stream gage (USGS number 8217500) was placed in the vicinity of, but downstream

of, the dam site in 1951 with a drainage area of 780 square miles. The average

annual streamflow for 1952 through 1985 at this gaging site approximates 380,000

af.

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1.3.2 Vega Sylvestre Reservoir Site

The Vega Sylvestre dam site is often considered an alternative to the Wagon Wheel

Gap site. The primary dam site is located on the Rio Grande mainstem approximately

17 miles upstream of the Wagon Wheel Gap site in Section 18, Township 40 North,

Range 1 West, New Mexico Principal Meridian. The reservoir proposed in the 1938

report would have required a saddle dam or dike west of the primary darn.

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The approximate location of the dam site is shown on Figure 1-2.

Maj or

characteristics of the reservoir proposed in the 1938 report are shown below:

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Table 1-2
Vega Sylvestre Reservoir Characteristics

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Storage capacity............................
Primary dam crest length....................
Primary dam height (above river level)......
Top of dam elevation above mean sea level...
Saddle dam crest length. ....................
Reservoir length............................
Drainage area...............................
Estimated Mean Annual Runoff (1948-85)......

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240,000 acre-feet
3,700 feet
125 feet
8,970 feet
2,700 feet
7.1 miles
528 sq miles
281,100 acre-feet

Previous studies have classified the site as a poor geologic dam site since it

would require extensive corrective designs to overcome inherently dangerous

characteristics (including a fractured left abutment and a right abutment so deep

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