Paper Released Aug 2, 2016
An Assessment of Demand Elasticity During Drought
by James Fryer
Read the full report [PDF, 16 MB] …
The primary goal of the study was to identify the extent short-term water use patterns during a drought were influenced by demand management programs undertaken by urban water utilities prior to such events. This included assessing if the long-term demand management programs resulted in decreased, increased, or no significant impact on the ability and willingness of urban water users to achieve additional demand reduction during subsequent drought events. The report is intended to provide a useful reference tool for urban water resource managers planning for and grappling with drought.
The report analyzed water use data from 1970 through 2011 for seven utilities in the Western states. Two of the case study utilities were in Northern California and two were in Southern California.
Collectively for a service area, water users typically met or exceeded conservation goals during drought events when given an actual target.
The report found no apparent evidence in the case study water use records that water users were having more difficulty meeting water use reduction targets in more recent droughts compared to drought events that occurred earlier in the 40-year study period.
Case studies experiencing drought in later years of the study period, when they were more saturated with conservation measures and had experienced substantial population growth, did not appear to have greater difficulty meeting water use reductions requested by their water utility.
If anything, water users appeared to more easily achieve the water use reductions requested by utilities during more recent droughts. However, the more recent drought events analyzed in the first edition of the report were typically less severe than some earlier or drought of record events. This new second edition of the report includes a brief review of the California 2015 drought. 2015 water use for the original four California case studies, and some additional utilities in California were reviewed. The utilities with service areas known to be more saturated with long-term conservation measures typically achieved equal or greater water savings in 2015 compared to the less conservation saturated service areas.
In assessing how water users respond and adjust water use during drought, it is important to recognize it may be a moving target over time. Water conservation technologies are undergoing continuous improvements. Efficiency improvements will continue to occur that will allow less per-capita water use in future years. Since the phone surveys of water users and saturation data indicate water users more rapidly adopt these during drought years, new efficiency technologies will provide new water use reduction opportunities in future drought years offsetting the potential for demand hardening.