WSP07539

• File Number: 8281.300
• Description: Colorado River Studies and Investigations - Colorado River Consumptive Uses and Losses Report
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/1991
• Title: Consumptive Uses and Losses in the Arizona Portion of the Upper Colorado River Basin for the Water Year 1990
• Water Supply Pro - Doc Type: Report/Study

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Consumptive Uses and Losses

3

55 inches per year1 or more. Elevations in the western portion range from
3200 feet on the Colorado River at Lees Ferry to over 8000 feet on the northern
edge of the Black Mesa and across the Zilnez and Skeleton Mesas, back down
to 5280 feet in the Chinle Valley, and back up to about 6500 feet on the
western edge of the Chuskas Mountains. Much of the western part of the study
area is starkly beautiful southwestern desert country with mesas and canyons
intertwined across a pastel landscape. By contrast, the eastern 1,000 square
miles is largely mountainous, with elevations rising to nearly 10,000 feet and
mean annual precipitation reaching 30 inches. The mountainous land responds
with grass meadows interspersed with conifer forest of mostly ponderosa pine.

The study area lies entirely within the Navajo Indian Reservation, except for
Page, Arizona; a small area around Lees Ferry; and a portion of the Paria
Plateau area administered by the Bureau of Land Management. According to
census data, 36,386 persons were living within the area in 1980, and of these,
31,429 resided on the reservation. From 1971-1980, the Navajo Reservation's
population growth rate was 2.15 percent. Assuming this growth rate continued,
the estimated population on the reservation for 1990 was 38,880.

The largest cities are Page and Kayenta, with 1980 populations of 4,907, and
3,343, respectively. Other major communities and their populations include
Chinle (2,815), Many Farms (1,364), Lukachukai (1,049), and Rough (311)."
Subsistence in this region is derived principally from livestock grazing, farming,
tourist-related industries, employment at the Navajo Generating Station, coal
mining at Black Mesa, and employment with the Federal Government or with
agencies of the Navajo Nation.

PUBLIC AND COMMERCIAL CONSUMPTIVE USES AND LOSSES

The consumptive uses and losses of water considered in this report only include
those related to the activities of people and are categorized as industrial,
municipal, domestic, agricultural (livestock watering and irrigation), or
reservoir and stock pond evaporation. The water consumed by the natural
vegetation and wildlife is not considered. The only major industrial
consumptive user is the Navajo Generating Station (NGS), which in the past
consumed a little over half of the water used or lost in the study area every
year. However, since 1990 was a dry year, industry accounted for 58 percent
of water used. Irrigated agriculture accounted for 10 percent of the total water

1 Lake evaporation data were taken from "NOAA Technicel Report NWS 33 Evaporation Atlas
for the Contiguous 48 United States," June 1982.

, 1980 Census data provided by Ron Faich, demographer for the Division of Community
Development of the Navajo Nation. In a communication received January 31, 1985, the Navajo
Nation contended that the 1980 United States census figure undercounted the population by
about 11 percent.