The first thing to remember about precipitation in California is that it’s unpredictable, as the past several winters have once again shown us.
Several years of severe drought ended in the 2016-17 winter with near-record rain and snow storms that filled the state’s badly depleted reservoirs.
The 2017-18 “water year,” as hydrologists call it, began with what seemed to be a return to drought but then, in March, the state experienced a steady stream of storms that added to the Sierra snowpack upon which Californians are so dependent.
It may not have been a “March Miracle” on the scale of 1991, when the mountains were virtually bereft of snow until one month of heavy storms ended the deficit. But what happened last month was at least a minor miracle, increasing the snowpack to more than 50 percent of average.
Combined with leftover storage from the previous year, California will enter the warmer months, when precipitation is rare, with fairly healthy water reserves.
Not only have the past several years demonstrated anew that “normal” is alternating periods of wet and dry, they also underscore just how dependent California is on its massive array of reservoirs, canals and other waterworks.
It collects water during the wet periods, as it did in 2016-17, and releases its reserves to maintain human life, wildlife and economy when conditions turn dry. Life as 39 million Californians know it would be impossible were it not for the state’s water system that federal, state and local governments maintain.
The state’s hydrologists believe that climate change will have a massive effect on our water supply in future decades, perhaps making the peaks and valleys of precipitation steeper and deeper and likely making more of it rain and less of it snow.
If, indeed, we will be getting more rain and less snow, it will degrade the snowpack as the state’s largest and most important reservoir. And that means we need to replace the snowpack with more man-made storage, allowing us to capture more winter rains that otherwise would flow to the ocean.
The need for more storage has been evident for decades, and although Southern California’s water agencies, particularly the Metropolitan Water District, have been diligent about adding it, Northern California, where most of the rain falls, has been negligent.
The last state water bond issue contained several billion dollars to jumpstart planning for new storage projects, particularly the off stream Sites reservoir on the west side of the upper Sacramento Valley and the Temperance Flat project on the San Joaquin River.
Together, they would add just over 3 million acre-feet of storage, or almost the equivalent of a new Lake Oroville.
However, state water officials have been somewhat lackadaisical about moving these projects along for reasons best known to themselves.
Meanwhile, there’s some movement on a long-standing proposal to raise Shasta Dam and expand Lake Shasta’s storage, now 4.5 million acre-feet – a project that is much more controversial because of its effects on land local Indian tribes consider to be sacred.
The recent drought was by no means the first. Gov. Jerry Brown’s first governorship four decades ago saw a very severe one. And it won’t be the last.
If we continue to drag our feet on building more storage, we will pay the price, and it will be a steep one.
Dan Walters is a columnist at CALmatters. Reach him at firstname.lastname@example.org.