California’s population has almost doubled over the past 4 decades, growing from 22 million people in 1976 to 40 million in 2016. During that time frame the state experienced four major droughts, including the driest period on historical record, from 2012 to 2016.
Now a new study examines how the public perception of water scarcity affects Californians’ urban residential water consumption. Although awareness of drought does reduce water use, that effect largely disappears once the perception of crisis fades unless more prevalent policies and messaging kick in to counteract the fading memories, the authors found. The study suggests that sustained attention from the media and policy makers is key to long-term water conservation.
California has seen a steady overall decline in per capita urban water use over the past 2 decades. This decline rapidly accelerated in 2015 because of Governor Jerry Brown’s mandate to collectively achieve a 25% reduction in water use from 2013 rates, with exact cutbacks varying among different utilities. But water use by utilities and consumers tends to rebound when the perception of drought fades and restrictions are lifted. When heavy rains hit during the last few months of 2016, for example, utilities were granted the flexibility to switch back to self-determined conservation goals, and roughly 80% of utilities reduced their conservation goal to 0%.
To isolate the effect of social awareness of drought on this rebound effect, Gonzales and Ajamiexamined data on nearly 4 decades of urban residential water use in three San Francisco area water utilities with significantly diverse socioeconomic realities. All three districts depend on the Hetch Hetchy Reservoir near Yosemite Valley for their water supply.
The team built a computer model to simulate changing public water use trends from both structural efficiency improvements and behavioral changes, the latter influenced by a range of factors such as policy changes, media coverage, and public awareness of drought. The authors found that during the recent drought, public awareness of the drought grew rapidly in the three utilities, contributing to unprecedented water conservation levels. But these savings started to rebound in 2016, especially in the higher-income communities that had a higher water demand baseline prior to the drought. The authors suggest this rebound is related to short-term conservation measures, like not watering lawns, rather than more prevalent changes such as shifting to water-efficient appliances or adopting water-saving behaviors in day-to-day practices.
Although this capacity to prompt significant short-term conservation is an important tool for utilities to address emergency conditions, the study highlights significant variability in drought responses and public attitudes from different communities, a source of uncertainty that challenges utilities’ finances and plans for the future.
Still, there are some commonalities. After California’s governor declared a drought state of emergency in 2014, all three utilities cut back their water use far more than in previous droughts. A previous state of emergency declaration in 2009, in contrast, received little media attention or public responsiveness, perhaps because an economic recession and a historic presidential election served as competing issues of public interest.
The contrast shows the power of public awareness to influence consumer behavior, the authors explained. Compared to previous water use lows of 63, 53, and 42 gallons per capita daily use (gcd) in 1991, for example, the three San Francisco area utilities in this study hit lows of 50, 45, and 35 gcd in 2015. The drop strongly correlates with local and state political actions such as the state of emergency declaration and subsequent drought-related publicity, the study found.
The results highlight a wide variety of responses to drought but also suggest that political action—and the media attention it attracts—can drive voluntary conservation across diverse communities, according to the authors. The reverse also appears to be true: When utilities and policy makers stop talking about drought, the public will to conserve water fades.
Although it’s still too early to tell how urban water demand will evolve in California following the recent historic drought experience, the authors suggest further public engagement about water resources could help counteract the effect of fading drought memories. This engagement could create a shift in public understanding of drought as a new normal and prompt more prevalent water conservation behaviors. (Water Resources