SFPUC Wholesale Customer Water Demand Projections ... - BAWSCA

SECTIONTHREE
Establishing Base - Year Conditions
Section 3 THREE Establishing Base - Year Conditions
3.1 INTRODUCTION
This section describes the development of base-year conditions for the typical SFPUC wholesale
customer in the DSS Model as depicted in the portion of Figure 2-1 above the dashed line. The
section explains how available demographic data, customer-billing data, and water use studies
were used to establish base-year conditions for the DSS model and characterize the water use for
each wholesale customer service area; and how these data were reconciled to estimate the
average number of users per account.
Appendix B includes a summary of customer-specific adjustments made in establishing baseyear
conditions and demand forecasting.
3.2 SELECTION OF BASE YEAR
The base year for this study is 2001. The base year serves as the starting year for the water
demand analysis and is used to establish initial conditions of water usage. The year 2001 was
selected over 2002 and 2003 for this study for three reasons:
• 2001 shows less of an effect of the economic recession. The year 2002 shows a dip in water
demand in many areas due to reduction in economic activity. This kind of reduction is
cyclical and demand generally rebounds in better economic times.
• 2001 had relatively “normal” climatic conditions (i.e., it was neither a drought nor an
excessively wet year).
• Records for 2003 were incomplete at the time of the analysis, which was started in mid-2003.
Figures 3-1a, 3-1b, and 3-1c show the water consumption for several SFPUC wholesale
customers from 1999 to 2002 that demonstrates the general trend of a dip in the year 2002.
Industrial, commercial, and multi-family water use was affected by the recession, particularly in
Silicon Valley. This dip was most likely due to a loss of jobs, exporting manufacturing overseas,
and reduced business, followed by the loss of workers who lived in apartments and moved out of
the area leaving abnormally high vacancy rates. Customer-billing data from 1999 to 2002
indicate that single-family water use was not affected by the recession.
The bold lines in Figures 3-1a, 3-1b and 3-1c indicate a 12-month moving average of the water
use for each wholesale customer graphed. Looking at the 12-month moving average, Figure 3-1a
shows that industrial use in Milpitas, Palo Alto, and Santa Clara started to decline in 2000, with
accelerated decline in 2001, and continued to decline through 2002. Reviewing the 12-month
moving average for commercial use in Milpitas and Palo Alto Figure 3-1b shows a nearly 10
percent decline in 2002 relative to 2001. Figure 3-1c shows similar declines in multi-family
water use during this period in Hayward and Milpitas.
3.3 WATER USE DATA
As discussed in the modeling approach, the DSS models were set up and calibrated using a
method that combines billing data, demographic data, and water use studies to establish the baseyear
model conditions for each wholesale customer service area. This section describes the steps
to get from total water production to end uses.
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