California is suffering through the worst drought in 1,200 years. So what are we doing about it?
In L.A., Mayor Eric Garcetti has called for a voluntary cutback of 20 percent. Sounds reasonable, except that history shows voluntary restrictions don't do much.
Actually, according to data compiled by Dr. Caroline Mini for her dissertation at UCLA, low-income people do conserve a little bit under voluntary drought restrictions. But rich people actually use a little more.
Mini looked at data from the L.A. Department of Water and Power from the last drought, which lasted from 2007 to 2010. During that period, the DWP imposed voluntary restrictions, then mandatory restrictions, and then finally raised the price of water.
As Adam Smith might have predicted, raising the price was the most effective way to reduce demand. Mandatory restrictions alone were less effective, and voluntary restrictions were pretty ineffective. But it gets really interesting when Mini breaks the data down by income groups:
This graph shows shows the effect of water-use restrictions, broken down by income categories. Low-income neighborhoods are represented by light gray bars, medium-income areas by dark gray bars, and high-income neighborhoods by black bars.
When voluntary restrictions were first imposed, in July/August 2007, low-income areas cut water use by 1.8 percent. Rich areas increased their usage 1.1 percent. In September/October 2007, low-income areas cut their use by 1.2 percent, while rich areas increased their use again by 1.1 percent. The disparity continued in May/June 2008, when low-income areas reduced usage by 4.2 percent, and rich areas increased by 0.5 percent.
It only started to even out — and then rich people started to conserve more than poor people — when mandatory restrictions and price increases went into effect.
Why should this be? Mini is at a loss.
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"We actually did not look into the factors that explain why lower-income and higher-income groups would respond differently to voluntary restrictions," she said via email.
It's clear that when it comes to water use, rich people and poor people are different. The key difference is that poor people tend not to have outdoor landscaping.
It is much easier to cut back on outdoor watering than indoor water use — which may explain why rich people conserve more once the price goes up. But it's a bit of a mystery why poor people would be more responsive to voluntary cutbacks than rich people.
"It makes sense that higher-income groups don’t change behavior until they get their bill in the mail," said Celine Kuklowski, a researcher at UCLA's California Center for Sustainable Communities. "Why lower-income groups respond to a call to reduce, I’m not sure."