PROJ00032

• Contract/PO #: C153465
• Contractor Name: City of Cortez and Dolores Water Conservancy District
• Contract Type: Loan
• Water District: 71
• County: Dolores
• Bill Number: HB 83-1102
• Loan Projects - Doc Type: Feasibility Study

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3-3

population. If the population projections are too low, the
facilities will prove to be inadequate and will need to be expanded
sooner than expected.

The 50-year annual average rate of growth in Cortez was 4.2
percent from 1930 through 1980. The growth rate from 1970 to 1985
was 1.6 percent per annum, indicating a slowing in the growth rate as
the absolute population grows. The average growth rate from 1980 to
1985 was 1.7 percent per annum. Growth rates experienced during the
1950s (9.7 percent per annum) are extremely high, are due to unusual
and nonpredictable economic development, and should not be used as a
basis for long-term facilities planning. There is a tendency for the
rural areas of Montezuma County to grow faster than the urban areas,
adding further to the slow down in the City's rate of growth.
Previous population projections are summarized in Table 3-2 and
generally show that the City is projected to grow at around 3.0
percent per annum.

Because of the importance of population projections, growth at
the rates of 2, 2-1/2, and 3 percent per annum were prepared to show
a range in which future populations may fall. This range is shown on
Figure 3-2, along with projections made by the USBR. The data is
also given in Table 3-3.

The historical rates of growth in Cortez have shifted markedly as
economic conditions change and immigration/emigration patterns
respond to these changes. The long-term (50-year) rate of growth has
exceeded 4.0 percent per annum, however recent growth rates have been
in the range of 2.0 to 2.5 percent per annum, depending upon the
population assessments used. Long-term projections (see Table 3-2)
have predominantly used a rate of growth of 3.0 percent per annum. A
figure of somewhere in the range of 2.5 to 3.0 percent per annum
growth is appropriate for use in this study.

Water Requirements

The average-day water consumption records are used to evaluate
the overall growth of the water system. System facilities, such as
the sources of supply, water treatment plant and pumping stations,
must have sufficient capacities to supply the average rate of the
maximum day. The distribution system (pumping stations, storage
tanks and water mains) must be able to deliver the required fire flow
with coincident demand. (The average rate of the maximum day is
utilized as the most severe coincident demand.) The distribution
system must also be able to meet peak-hour demands.

BROWN AND CALDWELL C CONSULTING ENGINEERS