"Given that California is experiencing an extreme drought and it's likely that we will be experiencing a lot more drought over time, it's very important to understand how water is used in the city and to identify areas where water consumption can be dramatically reduced," said Stephanie Pincetl, director of the CCSC and the project's principal investigator. "We know there is going to be more stress on water resources and that reducing water consumption does not really affect quality of life."
Pincetl and her colleagues plan to offer several recommendations to the Los Angeles City Council and the Los Angeles Department of Water and Power, including the adoption of household water meters that measure indoor and outdoor water use separately.
Other recommendations include:
Implementing a revised multi-tiered pricing structure for residential water use, aimed at increasing conservation while minimizing the cost burden on low-income consumers. One possibility would be a pricing structure with more than the current two tiers, in which the unit price for water rises as the volume of water consumption increases; another would be a combining an increasing block rate structure with seasonal rates, in which prices increase during the summer.
Establishing reasonable water budgets for households based on location and household characteristics. Homeowners who use more than their allotted amount would see increases in their bills.
Introducing educational programs and stronger financial incentives to promote the use of drought-resistant landscaping and improved irrigation.
Pincetl said that additional revenue generated by higher bills for heavy use and outdoor use could help pay for installing indoor–outdoor meters and other retrofits, and for strengthening lawn-replacement incentives.
The study that prompted the recommendations analyzed water-use data from 2000 to 2010. It revealed that a majority of the water used by L.A.'s single-family homes is used outdoors. The research was conducted by Caroline Mini, who earned a doctorate in civil engineering from UCLA in 2013, and funded by the National Science Foundation and a NASA Earth and Space Science fellowship.
"Outdoor water use accounts for 54 percent of single-family residential water use across the city," Pincetl said. "The greenness of the landscape did not change significantly when there were outdoor watering restrictions during the study period, which suggests that residents are overwatering when restrictions are not in place."
In general, water use is also sharply divided by geography and household income. For example, single-family homes in Pacific Palisades used, on average, more than twice as much water as those in the less-affluent neighborhoods of Leimert Park and Florence. (However, water use in Venice, where the median household income is roughly double that of Leimert Park and Florence, was lowest among the neighborhoods surveyed.)
The study found that higher prices for water are effective at reducing consumption and that mandatory restrictions are more effective than voluntary restrictions. For example, in July and August 2009, increased rates coupled with a mandatory water restriction issued by LADWP resulted in a 23 percent reduction in water use.
Pincetl supervised the project along with Terri Hogue, a former UCLA professor who is now at the Colorado School of Mines.
The study complements the first project of UCLA's Grand Challenges initiative, "Thriving in a Hotter Los Angeles," whose aim is to make Los Angeles a global model for urban sustainability by 2050.
"Within a large-scale project like Grand Challenges, this is the type of work that provides the scientific basis for good policy," Pincetl said.