PROJ00527

• Contract/PO #: FS0024X
• Contractor Name: Florida Water Conservancy District
• Contract Type: Loan
• Water District: 0
• County: La Plata
• Loan Projects - Doc Type: Feasibility Study

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and Reservoir are located along the southern edge of the San Juan
Mountains near the boundary of the upturned strata that forms the
outline of the San Juan Basin. The formations dip downstream
about 10-15 degrees around the dam axis. There are occasional
faults in the vicinity of the reservoir, but no faulting was
observed during construction.

Limestones, shales, siltstones, and sandstones of the Molas,

Hermosa, Rico, and Cutler Formations compose the bedrock of the

dam and reservoir area. These gray, red, and maroon beds range

from the Pennsylvanian through the Triassic Ages. These forma-

tions are well exposed on the valley sides, but are covered with

thick deposits of glacial till and outwash in the bottom of the

valleys. The valley sides are occasionally covered with landslide

and other colluvial deposits of variable thicknesses.

The topography of the area is steep and rugged, formed by

mountainous uplift and followed by intense glaciation. In the

reservoir area, more resistant strata form high ridges and the

softer beds usually form valleys tributary to the Florida River.

Elevations vary from 13,147 feet at the crest of Emerson Mountain

near the Florida River headwaters to 7925 feet at the base of

Lemon Dam.

5.2 VEGETATIVE COVER
The steep rugged slopes surrounding the reservoir are covered
with shallow soils over impervious bedrock. The typical vegeta-
tion occurring in this area includes ponderosa Pine, Douglas Fir,
and Colorado Blue Spruce associations, with the ponderosa Pine
association predominating the lower dry areas and the Douglas Fir
association occurring on the higher elevation sites. It is common
to find the Colorado Blue Spruce association where high water
tables are prevalent and along water courses.

5.0-2