C153362 Feasibility Study

• Contract/PO #: C153362
• Contractor Name: Trinidad, City of
• Contract Type: Loan
• Water District: 19
• County: Las Animas
• Bill Number: SB 81-439
• Loan Projects - Doc Type: Feasibility Study

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North Lake and Monument Lake have spillway elevations of
8583 and 8584 feet mean sea level (MSL), according to
U.S. Geological Survey topographical maps. The water
treatment plant is about 550 feet lower, at elevation 8026.
The City of Trinidad is still lower, at about elevation
6300 feet MSL. Six miles west of the Lakes, the Culebra
Range rises to over 13,000 feet, forming the watershed
divide between the Rio Grande and Arkansas River Basins.
The Purgatoire River provides the major drainage in the
general area. Trinidad's Mountain Water Supply System is
in the North Fork Purgatoire River drainage.

CLIMATE

The project area is in a lower mountainous area typical of
the front range of Colorado. A climatological data station
is maintained at North Lake, with temperature measurements
available for the past 20 years and precipitation measurements
for 82 years. Normal average daily temperatures range
from 25.60 F in February to 62.30 F in July. Precipitation
ranges from a normal of .87 inches in November and January
to 3.32 inches in July, with the average annual being
20.79 inches. Winter months in the project area are known
for deep snows, while summer months are cool, relatively
dry periods.

VEGETATION

The project area is on the border between an area known as
"woodlands of the lower mountains" and "woodlands and
grasslands of subalpine areas." An inspection of the area
indiciates stands of ponderosa pine intermingled with
grassland, in approximately a mix of 50/50.

GEOLOGY AND SOILS

The striking feature about the geology of the area is the
almost vertical formation of narrow limestone rocks that
form "The Stonewall" immediately east of Monument Lake and
to the west of North Lake. This geologic feature continues
south another 4 miles or more and gives its name to the
community of stonewall. The streams in the area, including
the North Fork Purgatoire River, cut through gaps in the
limestone formation. Immediately east of "The Stonewall"
are sedimentary rocks of Cretaceous age, primarily the
Pierre Shale, Niobrara, Carlile, Greenhorn, and Graneros
Formations. To the west of "The Stonewall" is sedimentary
rock of Permian and Pennsylvanian age, primarily the
Sangre de Cristo Formation, an Arkosic conglomerate,
sandstone, and siltstone material. The general soils
association in the project area is Cryoboralfs-Cryoborolls-
Cryorthents, which is a cold, deep-to-shallow, well-drained,
sloping-to-steep soil on mountain slopes and mesas.

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