President Donald Trump is obsessed with how California manages its water supply, demanding changes as one price of giving the state billions of dollars in aid to cope with Southern California’s deadly and destructive wildfires.
However, Trump’s specific complaints are not grounded in hydrologic or managerial reality — such as his insistence that a lack of water from Northern California was a factor in either the fires’ eruption or the firefighting efforts. Hydrants dried up largely because systems were designed to deal with individual structure fires, not widespread wildfires involving thousands of buildings.
That said, there’s much to criticize in how California, once a global leader in large-scale water management, has faltered. Population growth and evolving agricultural practices have increased demand, while state environmental laws, judicial decisions, political foot-dragging and climate change have restricted supply.
One major failing has been a slow response to an obvious need for more water storage — in reservoirs or underground aquifers — to capture rains and snowmelts as a buffer for dry years.
Scientists believe that even if California’s overall water supply from rain and snow doesn’t decline, wet and dry cycles have become more intense, and more precipitation is coming as rain instead of snow. Thus the natural reservoirs of snowpacks in the Sierra and other mountain ranges are becoming less dependable.
A new report from the Public Policy Institute of California points out that the atmospheric rivers that dropped immense quantities of rain and snow on the state this month, following a dry January, did not result in substantial new storage in reservoirs.
“Rather than storing all the water they can, during the winter reservoir operators are required to maintain enough space in their reservoirs to capture high inflows and reduce the risk of flooding downstream,” researchers Jeffrey Mount and Greg Gartrell wrote.
“When the February storms arrived, the surge of water into the state’s two largest reservoirs — Shasta and Oroville — quickly filled the flood reserve space. Because the winter flood season is far from over, dam operators had no choice but to let the water go to make space for possible future floods. And they let go a lot of water. Between Feb. 1 and 18, those two reservoirs alone released more than 2 million acre-feet of water into the Sacramento and Feather Rivers to maintain space for future stormwater.”
Overall, they calculated, 5.1 million acre-feet of water flowed into the Sacramento-San Joaquin Delta during that period in February. Just 4% of it could be diverted into storage.
Even a relatively tiny increase in storage capacity could pay huge dividends when wet winters such as this evolve into periods of drought. Had the long-proposed Sites Reservoir on the west side of the Sacramento Valley existed, it could have banked as much as 1.5 million acre-feet of that excess flow.
California’s water managers acknowledge the need for more storage to take advantage of high-precipitation winters, but clearing the legal and financial hurdles and building it takes decades.
The hydrological reality of California’s water supply is changing faster than our willingness to deal with it. The outcome of that disparity is perilous.
Dan Walters’ commentary is distributed by CalMatters, a public interest journalism venture committed to explaining how California’s state Capitol works and why it matters.
