Study details the ‘rigidity penalty’ in watering regulations

When the Truckee Meadows Water Authority was thinking about allowing people to water their lawns three days a week, rather than two, some engineers worried about the utility’s ability to meet sharply increased demand.

After all, they said, wouldn’t people boost their water consumption by 50 percent if they could water on three days, rather than the two-day watering schedule that had been in place for years?

Shawn Stoddard, a senior resource economist with TMWA, thought that the worries were misplaced when TMWA made the change in 2010. He was mostly right, and now Stoddard has joined with other researchers to explain the economics behind the reasons that increased options actually have helped TMWA meet demand more efficiently.

“Free to Choose: Promoting Conservation by Relaxing Outdoor Watering Restrictions” was co-authored by Stoddard, Anita Castledine of the Public Utilities Commission of Nevada; Klaus Moeltner of Virginia Tech and Michael Price of Georgia State University. (All have ties to the Univeristy of Nevada, Reno, and TMWA.) The study is published in the Journal of Economic Behavior & Organization.

As an economist who has taught at UNR alongside his work at TMWA, Stoddard strongly doubted that residents would take advantage of the additional day of watering to run their sprinklers even longer each week. After all, he asked, who’s going to spend money on water if they don’t have to?

“But it wasn’t enough to know it,” he says. “We proved it.”

The researchers’ big finding: One of the unintended consequences of the two-day-a-week schedule established in 1992 was what they call “a rigidity penalty.” Given that they had only two days in which they could keep their lawns green, TMWA customers almost always watered on those days — especially right before the four-day stretch each week in which they weren’t allowed to water at all.

That led to big inefficiencies. Folks would water on windy days, for instance, when much of the water wouldn’t reach their lawn. They felt they had no choice. The rigidity penalties may have driven as much as 25 percent of weekly consumption, the researchers found.

Once TMWA customers were given an additional day on which they could water, they watered more efficiently — skipping windy days, for instance.

More critically for TMWA’s finances, the addition of a third watering day reduced the peak demand on the water utility’s system. And that’s no small thing, because the capital investment of TMWA — or any utility, for that matter — is based on the need to meet peak demands.

“Everything is built for the peak day,” says Stoddard. “Anything we can do to reduce peak demand reduces capital costs.”

In the Reno area, the researchers found that the “rigidity penalty” associated with a two-day schedule may have contributed as much as 40 percent to weekly peak demands.

The research using TMWA data is likely to be useful as other utilities throughout the West look for ways to reduce water consumption in the face of longstanding drought conditions.

The additional choice provided by the third day also created a cheerier clientele — not that cheeriness matters to economists who practice the dismal science, but still ….

“People became happier because they had more choices,” says Stoddard. “And nobody had to give up anything.”