The cost of walnuts could be on the rise.

Flooding along the Sacramento River in the spring, followed by this week's heat amount to a one-two punch, leaving hundreds of acres of dead and potentially dying walnut trees.

If you've bought walnuts at a local Costco, there's a chance they came from Ricardo Garcia's orchard in Yolo County. He has been growing walnut trees there since he was a kid. His dad has worked the land for decades.

"It's our livelihood," he told ABC10 Monday.

The Garcias entered the winter season with 14,000 walnut trees. Now, they've lost more than 12,000 of those. Only 15 percent of their 500 acres of walnut trees remain.

"Best case scenario, with the trees that we have left, they survive and hopefully we can replant from that," Garcia said. "Worst case scenario, we lost more trees and unfortunately we might not have a farm left."

ABC10 spoke with Yolo County agriculture commissioner John Young.

As he explained, ongoing repairs to the Oroville Dam this year meant annual spring runoff wasn't handled like it usually is.

The Sacramento River level along Garcia's and other walnut growers' orchards stayed high through May, months later than normal.

That flooded those fields well into the growing season and drowned the walnut trees.

"It's gut-wrenching," Garcia said, walking past rows of skeletal trees. "At this point, they should be fully green. You know, the limbs usually are almost touching the ground because of the walnuts on them, and there's not even leaves on the trees at this moment."

He estimates this spring flood wiped out 85 to 90 percent of his trees. He recalled the flood of 1997 and one in the early 80s that were bad - but not nearly as devastating.

Because of the loss, he had to lay off four full-time workers.

"Then, come harvest, I mean, we had 20 people working for us," Garcia said. "They aren't going to be coming around either."

Garcia leases the land from the non-profit Yolo Land Trust.

"Our mission is simply to permanently conserve the farmland and rangeland in Yolo County," executive director Michele Clark said.

She said her organization's and the Garcias' situation is not unique.

"There have been other growers in Yolo County and also further north that have had damages or loss of trees," Clark said.

That's money lost for farmers, workers and the Yolo Land Trust. The non-profit relies on the revenue from the walnut sales to help keep the lights on, Clark said.

Plus, the dead trees mean fewer walnuts at the grocery store in the not-so-distant future.

"We did about 1.4 million pounds of walnuts last year. I'm going to be lucky if I get 10 percent of that this year," Garcia said.

This week's heat could kill off some of the trees that barely survived the flood and are now struggling to flourish, he added.

"I feel like the trees could've been saved if the water situation was handled a little bit better up at the dams, to where we had all winter to release water and, unfortunately, they held off until late spring to still release water," Garcia said. "That killed the majority of our trees."

Walnuts are harvested in the fall, so if there is an impact to cost and availability, we wouldn't see it until sometime next year.

A young walnut tree takes several years to produce a full crop, so these farmers have years of rebuilding ahead. The walnut supply at grocery stores could be impacted during that time, too.

Young said that he and other agriculture experts won't know for awhile yet to what degree the spring flooding along the Sacramento River will impact the walnut supply for shoppers. Roughly 20 percent of Yolo County's walnut crop comes from that damaged area of the county, however.