2013 Water System Plan, Volume II - Seattle City Clerk's Office - City ...

The graph below contrasts the official demand forecast with what it would be with constant flow factors and
with no future conservation of any kind (i.e., no price effect, no passive savings, and no programmatic
savings). Note that the forecast with “no conservation” is higher than the forecast holding water flow factors
constant over time because the “no conservation forecast” includes the impact of income growth and
changes in household size, which net to an increase in flow factors. For the 2013 WSP forecast, all sources
of conservation are estimated to produce a total reduction in water demand of more than 30 mgd by 2060.
200
Official Forecast Compared to
Forecasts with Constant Flow Factors or No Conservation
Annual MGD
180
160
140
120
100
80
60
Actual
Demand
Current Firm Yield
Official Forecast
No Conservation
Forecast
Constant
Flow Factor Forecast
The gray area represents the
added uncertainty involved in
extrapolating beyond 2040.
40
20
0
1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060
FINAL Page 13 of 22 December 2011