7142

• UCREFRP Catalog Number: 7142
• Author: Joseph, T. W., et al.
• Title: Evaluation of the Status, Life History, and Habitat Requirements of Endangered and Threatened Fishes of the Upper Colorado River System.
• USFW Year: 1977.
• USFW - Doc Type: \
• Copyright Material: NO

and Blue Mesa Reservoir on the Gunnison River. The development of Morrow
Point Reservoir on the Gunnison River in 1968 added 117,000 acre-feet of
storage.
Evaporation from the aforementioned reservoirs during 1965 was approx-
imately 648,000 acre-feet (Upper Colorado Region State-Federal Inter-Agency
Group 1971). Between 1971 and 1975, main stem regulating reservoirs re-
corded an increase of 10,156,000 acre-feet of storage (Bureau of Recla-
mation 1977). Reservoir evaporation rose to 741,200 acre-feet in 1975
with the six major reservoirs (Table 1.3) responsible for an estimated 89
percent of the loss (Bureau of Reclamation 1977).
Loss of water to reservoir evaporation accounted for over 19 percent
of the 3.82 million acre-feet of water depleted by man in the upper basin
in 1975. Nearly 82 percent of the reservoir evaporation comes from the
San Juan-Colorado Subregion. This loss principally from Lake Powell
although losses from Navajo Reservoir in New Mexico are also high when com-
pared to its surface area. Over half of the water used in the San Juan-
Colorado Subregion is lost to evaporation (Table 1.2).
Evaporative loss from the four other main stem reservoirs tends to be
less because of smaller surface areas, cooler waters, and a cooler climate
at higher elevations. Only eight percent and three percent of the water
consumed in the Green River and Upper Main Stem Subregions, respectively,
are lost to evaporation.
Other Uses
Uses of water other than irrigation, exports, and evaporation, account
for a relatively small percentage of the total volume depleted by man.
These uses include municipal and industrial needs, electrical power gener-
ation, mineral extraction, livestock needs, and stock-pond evaporation.
The discovery of gold and silver initiated the development of the
upper basin (La Rue 1916). In 1859, gold was discovered in Breckenridge,
Colorado, and soon mining camps were commonplace. Many miners, diasppointed
in their search for precious minerals, turned to ranching or farming. This
settlement brought.about dramatic increases in population and water use;
by 1940, the population of the upper basin had increased to nearly 275,000.
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