Lessons from California water conservation, 2019

Tough water times may be back in California. After the Golden State suffered through a historically severe drought from 2012-2017, pleasantly wet weather in 2018-2019 refilled reservoirs and replenished mountain snowpacks. But the state’s drought monitor shows that the past few months have trended drier, and water managers are worried that the state might be slipping back toward another drought.

One fortunate legacy of California’s recent struggles with drought is the California Water Board’s investment in data collection and dissemination. Researchers are learning important lessons about water management from that wealth of data on water consumption and conservation. Complete data for 2019 are now available, and I’ve just had a first look.

Three things emerge from my initial cut at the 2019 data that merit mention against the ominous backdrop of a looming drought.

1. A way of life

California’s overall urban water use remains down significantly from the pre-drought days. The state government established emergency conservation rules during the peak of the drought, cutting statewide urban water consumption by nearly 25%. But Governor Jerry Brown and other leaders also vowed to make water conservation “a way of life” that would extend beyond the emergency.

Californians seem to have taken the goal to heart, at least in aggregate. Though water conservation is not at the zealous peak we saw in 2015-2016, it remains strong:

Falling conservation in 2018 led to some hand-wringing, but conservation rebounded in 2019 to a statewide aggregate 18.1% relative to the state’s official 2013 baseline. That’s pretty remarkable and suggests that much of the reduction in California’s urban water demand is more or less permanent. Absent severe drought or monsoon-like precipitation, California’s overall water conservation will likely remain in the mid-to-high teens for the foreseeable future. That’s a public policy success story.

2. Persistent public-private disparity

One of the most fascinating findings that emerged from my earlier analysis of the California drought with Youlang Zhang and David Switzer was that the state’s private, investor-owned utilities conserved significantly more water than local government utilities during the drought.* We linked that difference in drought response to the institutions that govern water finance. We also found that the public-private conservation gap persisted even after the drought ended, with the greatest disparities during the summer when water demands are at their highest. Back in 2018 your humble blogger forecasted that that “public and private conservation will converge in the spring and diverge again in the summer and autumn.” And indeed, the pattern held: there was essentially no difference between public and private water utility conservation during the winter months, but during the 2018 May-September peak season, California’s investor-owned systems saved more water than their local government counterparts.

Did the pattern persist in 2019? In short, yes:

As you can see, public and private utility conservation move in pretty close parallel. During the non-peak period (January-April and October-December), there is essentially no difference in average conservation by ownership. But a public-private gap emerged again during the May-September peak period. In 2018 the difference was 2.3%; in 2019 the gap was smaller—investor-owned utilities saved an average of 1.5% more water than local governments. To give that percentage some context, think of it this way: if public utilities saved at the same rate as private utilities in 2019, the difference would have been about 15 billion gallons, roughly equivalent to the City of Long Beach’s annual water consumption.

The public-private disparity in summertime conservation now also appears to be a way of life in California. The difference is almost certainly related to pricing and revenue. Decoupling über alles.

3. Indoor outpacing outdoor?

In 2019 non-peak conservation crept up to 52% of overall savings. It’s hard to infer exactly what’s driving this pattern from aggregated monthly data, but the picture suggests that the most persistent water savings seen in California over the past five years has come from indoor efficiency. Average water consumption in 2019 was about 98 gallons per person per day (gpcd), but some cities are far lower. For example, water demand in conservative San Francisco shows hardly any seasonal peak at all, and averages just 42 gpcd—a level approaching the theoretical minimum to sustain developed world conditions.

While there are probably still plenty of savings to be had from indoor efficiency, meeting the challenge of another potential drought year—and driving further sustainable conservation—will require tackling peak demands through pricing and regulation. Get ready for another year of water cops and rate revolts.