Mandatory cuts in water usage have had a long-lasting impact on Californians, who have continued to espouse “water-wise” values even after such restrictions have been lifted, a new study has found.
Although water usage crept up somewhat when 2015-2016 cuts ended, consumption in 2019 was still lower than it was in 2013, according to the study, published on Tuesday in Water Resources Research.
The researchers attributed this shift in large part to a change in the behaviors of higher-end water users, who saw the greatest return from investing in water efficiency measures.
“They adopted technology in some way or another, and their rebound in water use was much smaller than lower-end use,” lead author Mehdi Nemati, an assistant professor at University of California Riverside’s School of Public Policy, said in a statement.
Such changes occurred after former Gov. Jerry Brown (D) imposed mandatory water cuts from June 2015 to May 2016 — a controversial executive order that forced water providers to slash urban use by 25 percent, following three years of worsening drought.
To achieve this goal, city utilities and water districts had to reduce water consumption by between 4 and 36 percent, depending on what conservation measures they had in place, the study authors explained.
Nemati and his colleagues focused on a Northern California water utility that serves about 70,000 people and then extrapolated the trends they observed to the entire state, by harnessing data from another ongoing study.
During the mandate period, the Northern California utility was required to decrease its water deliveries by 32 percent, the authors noted.
To accomplish this task, the company offered rebates to customers who planted drought-tolerant landscapes, updated irrigation systems and installed more water-efficient appliances. The utility also banned watering between 10 a.m. and 10 p.m.
“Consistent with best water-use practices, people moved to earlier watering hours, and continued to do so after the mandate was lifted,” Nemati said.
While the rules generally spurred Californians to embrace more conservative watering habits, the long-term results varied for different types of water users.
For example, although lower-end water users tended to let their lawns go brown during the mandate period, they generally resumed watering when the rules ended, the authors found.
Overall, residential water use decreased by 26 percent during the conservation mandate relative to pre-drought levels, but then rebounded about 9 percent post-mandate.
That rebound effect was greatest in the summer months and much more common among lower-end users, according to the study.
Moving forward, Nemati warned that it could become more difficult to achieve water-use reductions because so many higher-end users have already invested in water efficiency measures.
Nonetheless, he stressed that “it is useful for the water agencies to know that we already got rid of most of our low-hanging fruit.”