Experts Predict Bigger Swings Between Wet and Dry Years in California

There is no such thing as a ​“nor­mal” weather year in California any­more. Olive pro­duc­ers have to be ready for any­thing at any time. As Golden State farm­ers wrap up their 2023 har­vest and begin a new year, the water out­look is as uncer­tain as ever.

Predictions from the California Water Blog note that the main les­son of the wild 2023 water year is that California’s water sit­u­a­tion is highly vari­able, aver­ages are unre­li­able and improve­ments are needed to adapt to a con­stel­la­tion of inter­act­ing changes.

Anxiety and worry are often devoted to drought and water scarcity in California. Still, a new report from the State of California Department of Water Resources empha­sizes that grow­ers must not lose sight of the less fre­quent and shorter wet years.

“The real key here is long-term plan­ning. Seasonal fore­casts often get it wrong and aren’t yet equipped to deal with the next-gen­er­a­tion weather that we’re expe­ri­enc­ing,” Caitlin Peterson, the asso­ciate cen­ter direc­tor and research fel­low at the Public Policy Institute of California (PPIC) Water Policy Center, told Olive Oil Times.

“That means grow­ers must be ready for every­thing all at once,” she added. ​“They have to plan for the next extreme while in the cur­rent extreme.”

The PPIC Water Policy Center con­nects non­par­ti­san, objec­tive research to real-world water man­age­ment debates. Their work is designed to pre­pare for chang­ing con­di­tions and aims to improve cur­rent and develop future water man­age­ment prac­tices.

“We’ve seen in the past how the impacts of a given wet or dry cycle can vary across the state,” Peterson said. ​“Sometimes, this is a ran­dom vari­a­tion in weather pat­terns.”

For exam­ple, the drought that impacted the state from 2020 to 2022 ini­tially hit north­ern California the hard­est; by 2021, the impacts became more wide­spread.

Other times, the PPIC said this could reflect dif­fer­ences in plan­ning and coor­di­na­tion struc­tures across local and regional enti­ties, as with the dis­parate readi­ness lev­els for the 2023 floods seen across local gov­ern­ments.

The PPIC brief on drought and California agri­cul­ture out­lines this as a dynamic sit­u­a­tion of a fast-paced drought pro­pelled by cli­mate change, and the impact of new rules is reduc­ing water avail­abil­ity and increas­ing crop water demands. The volatile sit­u­a­tion includes dra­matic swings between pre­cip­i­ta­tion whiplash and megadrought.

“The north­ern half of the state is blessed with more abun­dant sur­face water and a smaller deficit in ground­wa­ter than the south­ern half of the state,” Peterson said. ​“Growers in the north may have more of a buffer and more man­age­ment options when deal­ing with weather whiplash. But there will still be chal­lenges, and grow­ers statewide should be think­ing about how to build their resilience.”

Peterson under­scored the reduc­tion of water sup­plies. ​“It’s impor­tant to keep in mind that grow­ers will have sig­nif­i­cantly less irri­ga­tion water to work with in the com­ing years, espe­cially in the San Joaquin Valley, where we esti­mate a 20 per­cent reduc­tion in sup­plies by 2040.”

A 2023 PPIC pol­icy report empha­sizes crit­i­cal issues for the future of agri­cul­ture in California’s San Joaquin Valley and the impend­ing reduc­tion in avail­able water.

Much of that reduc­tion is due to new rules designed to make ground­wa­ter extrac­tion sus­tain­able. This is con­sid­ered a vital facet of secur­ing a reli­able water sup­ply into the future.

“We esti­mate that at least half a mil­lion acres of agri­cul­ture land will come out of irri­gated pro­duc­tion by 2040 in the San Joaquin Valley,” Peterson said. ​“That means that regard­less of what the weather is doing in a par­tic­u­lar year, scarcity con­di­tions or sur­plus con­di­tions, on aver­age, grow­ers can count on less water.”

PPIC research on drought in California high­lights the vital imper­a­tive for agri­cul­ture to adapt, whether by find­ing ways to har­vest more water in wet years or by rethink­ing crop port­fo­lios and crop­ping sys­tems.

Wet con­di­tions can be highly costly to agri­cul­ture due to flood­ing, crop loss and dam­age to infra­struc­ture, yet farm­ers count on the wet years to get through the next dry years.

California’s farm­ers and olive grow­ers seek prac­ti­cal actions to respond effec­tively to the mer­cu­r­ial con­di­tions and seem­ingly non-stop del­uge of extremes. Peterson out­lined sev­eral actions for build­ing resilience by keep­ing all man­age­ment options on the table where pos­si­ble.

Olive grow­ers could upgrade their irri­ga­tion sys­tems to high-effi­ciency drip sys­tems. At the same time, grow­ers might also con­sider how to build sys­tems that quickly move large quan­ti­ties of water to fill an on-farm recharge basin with flood flows. A basin might sit idle for nine years out of 10 but must be imme­di­ately oper­a­tional before a high-flow event is under­way.

Irrigation sys­tems can be costly, but the hope is that well-main­tained sys­tems pay div­i­dends as part of a farm-wide water resilience strat­egy. Taking bet­ter advan­tage of the wet years in this way is a cru­cial strat­egy to help grow­ers get through the dry years.

To com­pound the issue, last year’s wet win­ter and flood­ing in California raised the pro­file of flood-MAR, or spread­ing excess water on agri­cul­tural lands to per­co­late into aquifers.

“This is putting money into our col­lec­tive ground­wa­ter sav­ings account,” Peterson said. ​“This ben­e­fits the grower directly when they can claim a por­tion of the water they recharged for later use, and it ben­e­fits the basin when ground­wa­ter lev­els improve.”

Olives have not been specif­i­cally stud­ied to gauge their tol­er­ance for short-term inun­da­tion, but it is pop­u­larly known that olive trees need good drainage.

“To pre­pare for this, olive grow­ers should be think­ing about alter­na­tive ways to take water dur­ing high-flow events, whether that’s build­ing a multi-use recharge basin or hav­ing a plan to divert water to more tol­er­ant crops on their acreage,” Peterson said. ​“Keeping some acres in annu­als is one way to do this, so you can have some flex­i­bil­ity on whether to plant or recharge.”

California olive grow­ers may need to adopt a new role, defin­ing them­selves as water har­vesters and look­ing for ways to store more water under­ground as a crit­i­cal facet of resilience to weather whiplash.

The PPIC noted that it is get­ting eas­ier for grow­ers to divert flood flows for on-farm recharge, yet many kinks still exist.

Several pol­icy changes could help California olive farm­ers adapt to the chang­ing cli­mate and ease the tran­si­tion to ground­wa­ter sus­tain­abil­ity.

According to the PPIC, the best thing grow­ers can do is be pre­pared, be informed on the per­mit­ting options and reg­u­la­tions and seek gov­ern­ment incen­tives where they are avail­able to help sup­port the kinds of invest­ments needed.

California’s chang­ing cli­mate con­di­tions con­tinue mak­ing head­lines, with grow­ers eval­u­at­ing how to best respond to loom­ing weather chal­lenges, from droughts to floods.

“I think peo­ple often assume that weather whiplash is a new phe­nom­e­non,” Peterson said. ​“On the con­trary, California has always had a pen­du­lum-style cli­mate that swings from wet to dry on a more-or-less 10-year cycle.”

“The dif­fer­ence now is that the swings are get­ting big­ger,” she added. ​“Dry years are get­ting hot­ter and drier. The jury is still out on whether wet years are get­ting wet­ter, but there’s some evi­dence to that effect.”

“We’re see­ing more of our annual pre­cip­i­ta­tion fall as rain rather than snow, which presents many chal­lenges from a statewide water stor­age and dis­tri­b­u­tion per­spec­tive,” Peterson con­cluded. ​“I think agri­cul­ture will con­tinue to sur­vive and thrive in California – but it might look a lot dif­fer­ent in 20 years than it does now.”

• Pleasanton Weekly