Image: Mostly TrueStatement: “To close driest year ever, water use last month in SD was up 25% over the same month a year ago. Do better,” Matt O’Malley of San Diego Coastkeeper wrote in a Jan. 30 tweet.

Determination: Mostly True

Analysis: California is in the midst of one of its worst-ever droughts.

As officials across the state urge water rationing, one local activist claimed San Diegans’ water use actually spiked at the end of last year.

Matt O’Malley, who oversees San Diego Coastkeeper’s legal and policy efforts, offered this cautionary message on Twitter on Jan. 30:

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O’Malley is basically claiming the San Diego region used a lot more water this December, just a month before Gov. Jerry Brown declared a statewide drought emergency.

Many water agencies across the state have pushed conservation in recent weeks but the San Diego County Water Authority has projected it has enough water in its storage reserves to get through the year.  O’Malley argues the Water Authority should take more aggressive steps to conserve now and over the long haul.

It’s worth taking a look at how county water usage has changed in the past decade before we compare this past December’s consumption with the same month in 2012.

Since 2007, Water Authority figures show regional water use has actually fallen about 22 percent. (The chart below doesn’t include 2008 numbers because they aren’t featured on the agency’s water usage page.)

The downward trajectory is even more evident when you analyze water use going back two decades.

Chart courtesy San Diego County Water Authority
Chart courtesy San Diego County Water Authority

The region is using slightly less water than it did in 1991, for example, when the county had roughly 2.5 million residents. The population is now closer to 3.2 million residents.

Among the drivers of these decreases are water-efficient home appliances and plants that fare better without lots of rain.

O’Malley, however, focused on a much more narrow comparison: December 2012 verses December 2013.

Indeed, Water Authority figures confirm  water customers from Carlsbad to San Diego used more H20 this past December than in December 2012.

In December 2012, county water customers used 29,177.8 acre-feet of water considered safe to drink. The following December, they consumed 36,660.1 acre-feet   – a 25.6 percent increase. Both figures exclude recycled water.

A significant decrease in rainfall this December contributed to the hike.

In December 2012, the National Weather Service recorded 2.19 inches of rain at the San Diego International Airport.

Weather Service spokesman Alex Tardy said that figure put San Diego nearly 50 percent above its normal December rainfall.

A year later, this past December, the Weather Service noted 0.46 inches of rain – just a third of the area’s average precipitation for that month.

So the two months that O’Malley compared were both outliers for December. The region saw significantly more rainfall than usual in December 2012 but significantly less than average this past December.

Dana Friehauf, the Water Authority’s acting water resource manager, cautioned against focusing too much on month-by-month water usage totals for that reason.

She argued the year-over-year totals reveal more about regional water usage trends.

Indeed, from 2012 to 2013, the region saw just a 2 percent overall increase in water use. Here’s how that played out over 12 months.

Still, Friehauf said, the lack of rainfall in December 2013 forced farmers and gardeners to use more water to maintain their crops and plants. Rainfall at this time of year usually helps them cut back on watering.

The Water Authority saw a 113 percent hike in water used by participants enrolled in its agricultural program.

Friehauf estimates more than half of the region’s agricultural users are enrolled in that system.

“It is amazing how much demand is influenced by weather especially when your economic livelihood is associated with keeping crops alive,” Friehauf said.

Those increases – coupled with those of countless San Diego-area homeowners who likely also kept watering their gardens in December – contributed to the water usage increase O’Malley noted.

And his claim that San Diego water use was up 25 percent in December 2013 compared to the same month in 2012 is accurate. However, it’s also worth noting that overall water usage for 2013 only spiked 2 percent when compared to the previous year.

The first part of his statement could mislead a bit more, though. He seemed to suggest that December 2013 marked the end of the driest year ever for San Diego.

This is certainly true for the state of California. A Weather Service spokesman said the statewide average precipitation level was just 7.4 inches, making it the driest calendar year ever recorded.

But San Diego wasn’t as hard-hit by drought as the state as a whole. San Diego’s 5.57 inches of rainfall in 2013 didn’t break any major records. Last year was the 13th driest calendar year for the San Diego area, which has a more arid climate than many other parts of the state.

O’Malley said he was focused on the statewide drought conditions when he made his claim but acknowledged he could have better clarified that in his tweet.

We label a statement “mostly true” when it’s accurate but there’s an important nuance to consider. That ruling fits here.

It’s true there was a 25 percent spike in water use in December 2013 over the previous year. But San Diego wasn’t experiencing its driest year ever, even if the state as a whole was.

And the San Diego region did use about 25 percent more water in December 2013 than in the same month the previous year, but the overall increase year-over-year was much smaller.

If you disagree with our determination or analysis, please express your thoughts in the comments section of this blog post. Explain your reasoning.

Lisa is a senior investigative reporter who digs into some of San Diego's biggest challenges including homelessness, city real estate debacles, the region's...

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