One year ago, the Food and Drug Administration warned Americans not to eat fresh spinach because it might be contaminated with E. coli.
The outbreak was eventually traced to a ranch near Salinas, Calif., but not before three people died and about 200 were sickened.
In the year since, the farms that produce California's leafy greens have started a new voluntary inspection program.
Mike Brown is one of about 10 new auditors with the California Department of Food and Agriculture. Today, he is trekking along the edge of a lettuce field near Salinas, Calif., when he spots some paw prints near the freshly irrigated field.
He says they look like dog tracks, but he is not sure. They could be from a fox or coyote.
"I don't see any footprints going into the field, so I'm just going to take a GPS reading from here and note that there were animal tracks," Brown says.
These field audits are staples of a new industry-backed program designed to minimize future contamination from sources like animals or tainted water.
Leafy greens handlers - or companies that send the product to market - sign up for the voluntary program. They agree to keep an eye on their growers and make sure they follow industry-written food safety measures.
"We always look at each well or water source on the property," says auditor Gordon Poulson.
He and Brown walk through fields to look for red flags: animal tracks, holes in fences, or farm workers who are not wearing gloves.
But they do not test water samples. The handler hires an independent testing company to do that. If a handler fails an audit - and that has not happened yet - the company risks losing its buyers.
Today, about a dozen workers are harvesting romaine lettuce. The handler's production manager, Lee Papazian, stands with Poulson at the edge of a nearby reservoir used for irrigation.
Papazian says if they see animal tracks, they would immediately perform tests before they watered again.
"And, to me, that's an example that this program is working," says Poulson. "Because you see the reaction that the growers take, the companies take. They don't have to be told to do anything. They're out there trying to do it on their own to make this product safer, as safe as it can be."
But the problem is, someone has to get sick before the public knows if the voluntary system is working, says state Sen. Dean Florez, who represents part of California's Central Valley.
Florez does not think a voluntary system is enough. He wants to mandate stronger food safety measures, such as, testing crops while they are in the ground and as they are harvested.
He wants state health officials to enforce the measures with fines for companies that do not comply, but his package of bills has stalled in the California legislature.
Florez says he is worried that until people get sick in another outbreak from contaminated food, the industry will continue to operate on a voluntary basis.
David Acheson, the FDA's expert on food safety, says it is impossible to eliminate food borne illness completely. Still, he says, the industry is on the right track.
"Do I believe that the leafy greens supply is a little safer than it was a year ago? Yeah, I think it probably is," he says. "Is it as safe as I would like it to be or the agency would like it to be? No, it probably isn't."
But for now that is all that is practical, he says.
Ben Adler reports from member station KXJZ in Sacramento, Calif.