Tightening Water Regulations in California May Spur Olive Cultivation

While irrigated olive groves still use plenty of water, increasingly strict prohibitions, especially in the San Joaquin Valley, may carve out a new niche for dryland olive groves.
San Luis Reservoir stores irrigation water for San Joaquin Valley farms. (AP)
By Thomas Sechehaye
Dec. 14, 2023 18:18 UTC

Despite the devel­op­ment of El Niño in the east­ern Pacific Ocean result­ing in a wet 2023 for California, cli­mate experts antic­i­pate the Golden State to con­tinue becom­ing hot­ter and drier.

According to the office of Governor Gavin Newsom, hot­ter and drier weather con­di­tions due to cli­mate change could reduce the state’s water sup­ply by up to 10 per­cent by 2040.

Olive trees will use plenty of water if they’re irri­gated fully; whether or not a grower is con­serv­ing water depends on how they man­age the orchard, which is not always easy to get right.- Caitlin Peterson, asso­ciate direc­tor, PPIC Water Policy Center

The Public Policy Institute of California (PPIC) esti­mates that 40 per­cent of all the state’s water is used in agri­cul­ture. As the state enacts tougher water reg­u­la­tions and encour­ages improved water use effi­ciency, some farm­ers are already bet­ting on drought-resilient olives as a crop of the future.

Olives are not the only tree crop out there that can with­stand a lit­tle deficit irri­ga­tion, but olives stand out for their drought tol­er­ance,” Caitlin Peterson, the PPIC Water Policy Center’s asso­ciate direc­tor, told Olive Oil Times.

See Also:Olive Trees Can Help Beat Climate Change

They can grow on very mar­ginal land with poor soils, some­thing that can’t be said for many of the dom­i­nant tree crops in California, such as almonds, wal­nuts or stone­fruit,” she added,

According to Peterson, both table and oil olives are drought-resilient. Table olives can quickly recover fruit size after a tem­po­rary reduc­tion in irri­ga­tion, even up to a 50 per­cent reduc­tion in mid­sum­mer. However, they can with­stand even more severe reduc­tions with a small (ten per­cent) yield reduc­tion.

With oil olives, some water restric­tions are ben­e­fi­cial because they keep veg­e­ta­tive growth in check to enable the orchard to be grown in hedgerows. Water stress can reduce the size of the fruit, but this is less impor­tant for oil pro­duc­tion.

While you don’t see this often in California, olives were tra­di­tion­ally grown in dry farm­ing sys­tems,” Peterson said. This meant no irri­ga­tion and spac­ing trees out to avoid com­pe­ti­tion for soil mois­ture.”

The fact that olives are well suited to that kind of sys­tem says a lot about their adapt­abil­ity and the poten­tial to make man­age­ment adjust­ments for con­tin­ued pro­duc­tiv­ity even under water scarcity,” she added.

According to Peterson, dry-farmed olives have yet to prove eco­nom­i­cally viable in California. Still, there may be more scope for them as the avail­abil­ity of irri­ga­tion water declines in some areas.

Olive water sys­tems have emerged in the con­text of recent drought con­di­tions in California and ongo­ing con­cerns about drought.

Peterson said the evi­dence is clear that cli­mate change is lead­ing to more fre­quent and intense droughts in California.

Hotter droughts pull more water out of soils and veg­e­ta­tion, which can cre­ate a cycle of plant stress that fur­ther inten­si­fies drought con­di­tions.

A detailed PPIC pol­icy brief high­lighted the issues regard­ing drought and agri­cul­ture and their impact, espe­cially in California’s San Joaquin Valley.

PPIC empha­sized that ongo­ing drought has the impact of reduc­ing water avail­abil­ity and increas­ing crop water demands. The brief described the dynamic sit­u­a­tion, a fast-paced drought – fueled by cli­mate change – is con­strain­ing water avail­abil­ity and increas­ing crop water demands.”

The con­cern with extended droughts like the one we saw from 2012 to 2016 is that you can’t skip a sea­son of irri­ga­tion on a tree crop,” Peterson said. We saw a lot of almond orchards get­ting pulled out dur­ing that drought because grow­ers didn’t have the water and couldn’t afford to main­tain them if they weren’t pro­duc­ing.”


That’s a big loss if your trees aren’t already near­ing the end of their pro­duc­tive life,” she added.

Groundwater is another fac­tor to con­sider when it comes to water sup­ply. Groundwater used to be the drought reserve for grow­ers. When sur­face water became scarce in the past, grow­ers could make up the dif­fer­ence by pump­ing as much water out of the ground as needed.

That is not pos­si­ble now because California is start­ing to imple­ment the Sustainable Groundwater Management Act of 2014.

The pump­ing cut­backs that will occur to bring ground­wa­ter use to sus­tain­able lev­els are crit­i­cal for the long-term via­bil­ity of agri­cul­ture, espe­cially in areas like the San Joaquin Valley,” Peterson said.

However, she warned that between 200,000 and 365,000 hectares of irri­gated land, about 10 per­cent of the total in San Joaquin Valley, could come out of pro­duc­tion to reduce demand.

We esti­mate a 20-per­cent reduc­tion in water sup­plies rel­a­tive to what we’re cur­rently work­ing with by 2040 in the San Joaquin Valley alone due to the com­bined effects of the Sustainable Groundwater Management Act, cli­mate change and more strin­gent envi­ron­men­tal reg­u­la­tions,” Peterson said.

When you add a drought on top of the Sustainable Groundwater Management Act, things get even more dif­fi­cult to man­age,” she added. My guess is you may start to see more olive orchards in mar­ginal areas that can no longer sup­port the thirstier trees.”

A report on Sustainable Groundwater Management Act-related water sup­ply reduc­tions fore­casted that the tran­si­tion would be chal­leng­ing.

Efforts to aug­ment water sup­plies include ground­wa­ter recharge, water trad­ing and meth­ods to man­age increas­ing water scarcity. Even in the best-case sce­nario, Peterson under­lined that approx­i­mately 202,000 hectares may need to be fal­lowed in the San Joaquin Valley.

Promising alter­na­tive land uses may involve solar devel­op­ment, water-lim­ited crop­ping, habit restora­tion, recharge basins and water-effi­cient new hous­ing, as out­lined in the report.

Peterson noted well-doc­u­mented research and guid­ance on reg­u­lated deficit irri­ga­tion avail­able for olive farm­ers. She advised that uni­ver­sity resources are an excel­lent place to learn about spe­cific prac­tices.

These resources can give olive farm­ers a pre­cise idea of how much irri­ga­tion can be cut back when water is short and the appro­pri­ate growth and repro­duc­tive stages in which to do that.

Olives are not as sen­si­tive to the tim­ing of deficit irri­ga­tion as other tree crops. However, Peterson advised that some stages are still bet­ter avoided if pos­si­ble.

Some per­sis­tent myths regard­ing olive water sys­tems and water usage in California are hard to shake.

Olive trees will use plenty of water if they’re irri­gated fully; whether or not a grower is con­serv­ing water depends on how they man­age the orchard, which is not always easy to get right,” Peterson said.

I also think that peo­ple tend to focus too much on increas­ing the effi­ciency of irri­ga­tion sys­tems as the key to using less water,” she added. More effi­cient deliv­ery sys­tems help reduce water use on a per-acre basis, but we for­get that that may allow a grower to plant more acres because they’re using less water per acre. The key is to look at total water use, not drops per acre.”


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