San Francisco – The effects of California's drought could soon hit the state's food banks, which serve 2 million of its poorest residents.

Fresh produce accounts for more than half the handouts at Bay Area food banks, but with an estimated minimum of 500,000 acres to be fallowed in California, growers will have fewer fruits and vegetables to donate.

With less local supply, food prices will spike, increasing as much as 34 percent for a head of lettuce and 18 percent for tomatoes, according to an Arizona State University study released last week. With fewer fields planted, there could be as many as 20,000 unemployed agriculture workers who will need more food handouts, especially in the Central Valley.

And if urban food banks such as those in Oakland and San Francisco can't get produce from the valley, which grows a third of the nation's fruits and vegetables, their transportation costs to haul in out-of-state produce will soar. Sue Sigler, head of the California Association of Food Banks, calls it "a perfect storm" of drought-related factors.

"It's not like we can raise our prices — everything is free," said Paul Ash, director of the San Francisco/Marin Food Bank, which distributes 149,000 meals a day across the two counties. "Not knowing [what the drought's effect will be] is a real frustration. We have to be planners, and it's hard to do that right now."

The Alameda County Community Food Bank expects to distribute roughly 17.8 million pounds of produce next year — about 14.5 million of that amount via the California Association of Food Banks. The Alameda County food bank pays 11 cents a pound to cover picking, packing and freight costs. Even a one cent per pound increase could mean $145,000 in additional costs. With an annual budget of $12 million, the organization can't take too many hits like that.

"There's absolutely a lot of nervousness here," said Allison Pratt, director of policy and services at the Alameda County food bank.

Also nervous is Mark Johnson — a Castro Valley father of two who visits three food banks a month, including one at South Hayward Parish in Hayward operated by the Alameda County food bank.

Fresh produce "would cost me $150-$175 a month if I had to buy it," said Johnson, toting two paper bags of celery and oranges. He said he relies almost exclusively on food banks for his produce because "my income's not going up." Johnson, 58, does some freelance video production and manages an apartment building in exchange for rent.

Just ahead of him in line last week were Cathy Garcia and her 3-year-old son, Bryan. For the past six months, she has stopped by the South Hayward Parish. They've needed extra help as her husband struggles to pick up construction and landscaping work.

Garcia is 8 ½ months pregnant and wants to keep eating healthfully, so she relies on the produce from the pantry. She doesn't have the $50 a month it would cost her to buy the produce she receives from the pantry and elsewhere. "Oh, no, it would be too much," Garcia said.

The drought's biggest impact will be in the Central Valley, where some food banks are already working to change their distribution strategy. They don't want a repeat of what happened five years ago, when the peak of the last drought coincided with the housing meltdown.

The Fresno-area towns of Firebaugh and Mendota were particularly devastated, with more than a third of the population out of work. People would begin lining up at 3 a.m., hours ahead of when food pantries were scheduled to make their bimonthly distributions. Those who arrived late received little or nothing until the next shipment landed two weeks later.