PUB00013

• Year: 1985
• Title: Estimated Use of Water in Colorado 1985
• CWCB Section: Water Conservation & Drought Planning
• Author: David W. Litke and Cynthia L. Appel
• Description: Water-Resources Investigations Report 88-4101
• Publications - Doc Type: Brochure

Where no delivery information was available, an estimate of 35 gallons per day
per person served was used, which is an approximate average of delivery data
that were available. When unknown, the source-type for self-supplied
commercial water was assumed to be ground water because records from the State
Engineer's Office indicate very little surface water is withdrawn directly for
commercial purposes. Where no site-specific data were available, consumptive
use for commercial users was estimated to be 15 percent of water used; actual
consumptive use varies from negligible for many small stores and businesses to
about 50 percent for large office towers where water is consumed primarily as
make-up water for air-conditioning equipment.

There is little published information about commercial water use; in most
instances, it is included with the industrial category. Commercial water use
amounted to 120 million gallons per day during 1985; it ranged from 0.01
million gallons per day in Costilla and Dolores Counties to 37.0 million
gallons per day in Denver County. Ninety-three percent of this quantity is
supplied by public-supply systems. Although self-supplied commercial water
withdrawals generally are small, large withdrawals do occur in Garfield County
where hot spring water is withdrawn and passed through several large
commercial spas. About 20.8 million gallons per day was consumptive use.
Tabular summaries of commercial water-use data are listed in table 5 (for
counties) and table 16 (for hydrologic subregions) in the "Supplemental Data"
section at the back of this report.

Domestic Water Use

Domestic water use includes water used for inside household purposes,
such as bathing, drinking, flushing toilets, food preparation, washing clothes
and dishes, and for outside household purposes, such as washing cars and
watering lawns and gardens. Data were collected for this category for
water-source type, water-supply method, water-disposition type, and population
served (by source-type and by water-supply method). Per person use rates also
were calculated.

Data about deliveries to domestic users and population served by these
deliveries were obtained from public-supply systems. These data were compiled
for each county cataloging unit. Consumptive use was estimated to be 30
percent of delivered domestic water. This estimate is based on the assumption
that about 40 percent of all domestic deliveries are used for lawn watering in
metropolitan areas (U.S. Army Corps of Engineers, 1986a, p. 40), that somewhat
less water is used for lawn watering in mountain areas, and that most water
used on lawns is consumptive use. Very little water used indoors is consump-
tive llse.

The remaining population of a county cataloging unit was assumed to be
self supplied. This assumption was verified by examination of the number of
wells permitted for domestic use in each county cataloging unit--multipli-
cation of the number of wells by the average number of persons per household
(estimate of 2.6 used) should be approximately equal to the number of
self-supplied persons. A withdrawal rate of 75 gallons per person per day was
assumed for self-supplied domestic users. Consumptive use for self-supplied
domestic users was assumed to be 10 percent of withdrawals. This is the

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