SOAK IT UP

What the six-year drought did to California in 93 maps and two charts

After six years, the California drought is officially over. The National Drought Mitigation Center has determined that just 9.3% of the state is considered to be in “moderate drought” or worse as of April 11. California governor Jerry Brown lifted the state of emergency (pdf) regarding the drought in all but four counties on April 7.

An influx of moisture over the last few months has caused growth in flora all over the state, even in the deserts where typically brown mountains have turned green with vegetation.

January 2014

January 2017

Data: Aqua Modis/NASA LP DAAC

Superficially, this can be seen in the color of the state. Satellite imagery compiled by Quartz show California, and especially the agriculture-heavy Central Valley, as a deeper shade of green now than at any other time since the beginning of the drought.

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Data: Aqua Modis/NASA LP DAAC

The drought caused tough times for industry and agriculture, which, facing local water-use restrictions, was forced to truck in water from elsewhere or drill deeper wells. In other states these restrictions might only have local or regional effects, but in California the repercussions spread far and wide. The state produces 11% of the US’s agricultural output and grows 51% of the country’s fruits and vegetables by value, as of the most recent USDA agricultural census conducted in 2012.

Let’s take a look at the three factors scientists have been using to evaluate California’s drought and how they’ve changed over the last six years.

Snow Pack

The snow that covers the Sierra Nevada and Trinity mountain ranges are a store of moisture for the whole state. Snow that falls in the winter melts through the spring and summer, seeping into the ground or flowing into rivers. The majority of California’s drinking water comes from the Sierra Mountains’ snowpack.

On April 1, 2017 the California snowpack was at 164% of normal. That’s well above the totals from previous years. It has been six years since officials measured above-average snowpack on April 1.

Surface water

Melting snow and falling rain ends up in rivers, which feed reservoirs that store water for use all year. As of March 2017, 51% of stream gauges in the state show water flowing at or above their long-term average level. At the same time in 2014, that figure was just 11%.

River flows

Data: USGS

California has been exceptionally rainy this year with many locations around the state experiencing floods. Six months into the current October-to-September water year, the state has received 144% of its average annual precipitation. The season is currently California’s wettest on record.

Another measure of surface water is the levels of reservoirs. During the drought, those sank to dire levels.

Reservoir levels

Data: California Department of Water Resources

Reservoirs around the state are full again. Ten of California’s 12 major reservoirs are above their historic average. In December 2015 all were at less than 50% of their historical average.

Ground water

The level of water in the ground is still a matter of concern. Increased reliance on pumping water out of the ground has left wells—and thus groundwater—far below normal.

Note: Wells are measured sporadically and on differing dates. Data: California Department of Water Resources

Researchers at the US Geological Survey found that parts of the Central Valley was sinking two inches a month during the drought as farmers and others pumped water out of the ground faster than it was replenished. Continued change in ground level could wreak havoc on existing infrastructure. Roads, pipelines, and canals could all fail as the land beneath them shifts.

Already, the ground has sunk enough that operators of the California Aqueduct must reduce flow in certain areas by 20% to account for grade changes.

Recently, farmers have started to be more proactive about trying to replenish groundwater. Some have taken to flooding their fields with stormwater with the hope that as the water seeps into the ground it will recharge the aquifer beneath.

For now things are looking up. 2017 will be the first year since 2006 that farmers in the Central Valley will be granted a full water allotment by the federal Bureau of Reclamation.

But the outlook for California’s water future is uncertain. While the drought emergency has been declared over, many of the restrictions on water use remain in place, and with the unpredictable weather patterns brought on by climate change, California could end up back in a new drought as soon as next year.

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