8.2.6  Seattle Conservation and Curtailment

Conservation is the combination of policies and programs that provide equal service with less drinking water.  Seattle Public Utilities developed the "Long Range Regional Water Conservation Plan" in 1996 to reduce demand.  This strategy includes higher summer water rates, plumbing fixture codes, operation improvements, customer rebates and financial incentives, and education.

In 1999, Seattle City Council approved a 1% conservation program that will decrease projected water demand by 1% per year, for ten years.  The purveyors did not approve a similar conservation goal, but they still practice conservation and have decreased water usage per household over the last ten years.  The Seattle Demand Forecasts section discusses demand projections and conservation demand projections.  The CYSTAL model can incorporate the 1% demand projections, when the user selects this option.

Curtailment measures differ from conservation because they involve adverse impacts on customers for a limited time.  SPU has developed a drought contingency plan in which five levels of water-use curtailments can be implemented.  The timing and levels of the curtailments have not been specified but would be a function of the time of year, system demand, and reservoir level. The curtailment plan has been simplified in CRYSTAL.  It does not include "emergency" levels of curtailment.  Instead, curtailments in the model are represented with water demand reductions of 15, 25, and 35% and are dependent on time of year and weeks of stored supply remaining.