S5_11-15-04

• Basin: Statewide
• Title: SWSI Phase 1 Report - Section 5 Projected Water Use
• Date: 11/15/2004
• Author: CWCB
• SWSI - Doc Type: Final Report

Section 5
Projected Water Use
~
5.1.1.3 Estimates of Per Capita M&I Water Use
Numerous factors affect per capita water use rates, and
through the course of SWSI, differences in the water use
components that are included or excluded from individual
entities' per capita estimates clearly affected the resulting
values. Per capita water use rates are in large part a
function of:
^ Number of households
^ Persons per household
^ Median household income
^ Mean maximum temperature
^ Total precipitation
^ Total employment
^ Ratio of irrigated public land areas (e.g., parks) to
population in service area
^ Level of tourism and/or second homes
^ Ratio of employment by sector (e.g., agriculture,
commercial, industrial)
^ Urban/rural nature of county
Several sources of information were consulted in
estimating per capita M&I water use. The CWCB's
Drought and Water Supply Assessment study's
database was used as an initial data source, and
was supplemented in SWSI by sending a follow-up
survey to more than 200 water providers. Including
the responses to the follow-up survey, the resulting
database used in SWSI includes nearly 250 water
providers covering most of the state, as indicated in
Figure 5-2. Regression analyses of available data
indicated that location was the dominant factor in
determining the variation of per capita water use
among the sample data.
~----e, - , ~ e .
'~°~r~~ .. , .
1~~~_~ . e aer' °ee °
.~
,~ e .
r} ~. ,
,~ . , , ;,
w, < , ~ ~.
-~~ , - - ~
. ° ~$ ~ ~t~ , __
~ l .
. ~,_' ,,. ~%~ .,
`' _.r' ~~ ~
~~ ~_,, .
. ~- e , -
. e ~ ~~ ~ ~ . e
Figure 5-2
Providers in SWS/ per Capita Demand Database
~~
The provider per capita values in each county were
weighted by their respective populations to produce a
weighted average per capita value by county. In addition,
the weighted average per capita water use per basin was
also calculated. The basin weighted average per capita
rate was used for areas of the county that did not have
representation in the sample database. The underlying
assumption is that water use will be similar throughout
the county. The estimated county gallons per capita per
day (gpcd) water use rates were multiplied by the county
population projections to derive the estimated M&I water
forecast for each county. These M&I forecasts are shown
in Section 5.2 and the methodology employed is
explained in detail in Appendix E.
The sample data provided a per capita water use rate for
58 of the 64 counties within the state. The aggregated
basin average per capita water use estimates are
depicted in Figure 5-3; county per capita estimates are
listed in Appendix E. Overall, the population-weighted
average per capita M&I water demand for the state was
estimated to be 210 gpcd for the year 2000.
21

22
2 44

6
26
206
2 0
32
Arkansas
Colorado
Dolores/San Juan/San Miguel
Gunnison
North Platte
Rio Grande
South Platte
Yampa/White
0 50 100 150 200 250 300 35C
Average Per Capita M&I Water Use (gpcd)
Figure 5-3
Estimated Year 2000 Average per Capita M&I Water Use
This estimation of county per capita water use assumes
that all residences, businesses, and industries
throughout a county (including most self-supplied users)
use water at the same rate as the provider-supplied
residences, businesses, and industries as represented in
the sample database. Where data were available
regarding unique large self-supplied water users in
specific counties, these self-supplied water uses were
added to the county M&I water demand estimate, as
described in the following section.
~~
Sfvtewide Woter Supoly Initiofive
~J-4 S:\REPORT\WORD PROCESSING\REPORT\SS 11-7-04.DOC