We'd probably like to think that clean, safe food goes hand in hand with pristine nature, with lots of wildlife and clean water. But in the part of California that grows a lot of the country's lettuce and spinach, these two goals have come into conflict.
Environmental advocates say a single-minded focus on food safety has forced growers of salad greens to strip vegetation from around their fields, harming wildlife and polluting streams and rivers.
The heart of this conflict is the Salinas Valley, on California's central coast. And my guide to the valley, on this beautiful spring day, is Daniel Mountjoy, an ecologist with a nonprofit organization called Sustainable Conservation. "I just love the drive down through here," Mountjoy says, as we head southeast from Castroville, the self-proclaimed "Artichoke Center of the World."
We can see mountains to the east and the west, but the valley itself, miles wide, is as flat as high-tech field-leveling machines could make it. The Salinas River meanders down the middle of the valley, visible as a thicket of trees.
But most of what we see, though, is mile after mile of fields. Some are bare, ready for planting, others with rows of green leaves just emerging from brown dirt. This is one of the country's biggest sources of fresh lettuce and spinach. It's often called America's salad bowl.
And for the past 40 years, this valley has been the scene of a struggle to find a balance between some of the most intensive farming in the world and what's left of nature.
When Mountjoy first came here, as a student, almost 40 years ago, farming had already taken over.
"One of my professors brought us out on a field trip," he recalls. This scientist had invented some of the first chemical herbicides that farmers used to kill off weeds. "He was very proud of the fact that farmers had been able to eliminate and restrict all noncrop vegetation from the farms, and pointed out that you could tell a good farm from a bad farm by that fact that, from fence post to fence post, the only thing that was growing was the crop."
Mountjoy, though, found it bleak. Ecologically, it was impoverished. There was barely any food or shelter for insects, or the birds that feed on them, or bigger animals that need even more space.
Also, when it rained, soil and fertilizer washed straight into drainage ditches, streams, and the Monterey Bay.
Mountjoy became part of a movement to change that. He went to work for the Natural Resources Conservation Service of the U.S. Department of Agriculture. It's the arm of the USDA that promotes environmental quality. And for almost 20 years, part of his job was encouraging farmers in this valley to create a greener, more diverse landscape.
He stops the car to show me an example: a drainage ditch, almost 2 miles long. Ten landowners agreed to cover the bare dirt banks of this stream with grass. The grass held soil in place and captured fertilizer runoff that would otherwise have polluted the bay.
"So it was a green swath all the way through the valley, and it represented a real advance toward water-quality protection," says Mountjoy.
In other places, farmers took hillsides, or the margins of fields, and planted vegetation that was specifically selected to be a good home for insects — especially insects that actually help farmers by gobbling up pests like aphids.
There were even visionaries who talked about creating corridors of wildlife habitat across the valley, so that animals could migrate from the mountains on one side over to mountains on the other.
Then, six years ago, a food safety crisis shook the Salinas Valley.
Bags of pre-washed spinach from this area, shipped to many places across the country, killed several people and sent hundreds more to the hospital. The leaves had been contaminated with a deadly kind of E coli bacteria.
Those microbes can be carried into a lettuce or spinach field by wild animals — even little mice that might find shelter in grass along drainage ditches.
The leafy-greens industry was determined to eliminate that risk. And Mountjoy watched his green swath disappear.
"The farmers increasingly were being told, 'This is a potential risk to your operation,' " he recalls. "And one by one, the producers came in, sprayed it with herbicide, and returned the ditch to its bare dirt condition."
It wasn't just this ditch. Across the valley, trees, grass and hedgerows disappeared. So did ponds that might attract ducks and geese. Farmers built fences along the Salinas River channel, to keep wildlife that lives there from crossing into fields.
That campaign has been a success, in one way. During the past few years, there have not been any more big national outbreaks of disease that were traced to leafy greens.
But many environmentalists, and even some vegetable growers, believe that this campaign for food safety has also been reckless and sometimes needlessly destructive.
Among them is Bob Martin, general manager of Rio Farms, in King City. Martin grew up here and has grown vegetables for nearly his whole life. He doesn't call himself an environmentalist, but when food safety experts from the big food buyers told him to clear away vegetation on hillsides, he refused.
"People know me as a fighter; I'm not going to give in to everything," he says. "It goes against my nature to have the scorched earth policy. To have bare banks, so every time it rains you've got to bring in a bulldozer and push the dirt back up. Makes no sense! Erosion control is a healthy thing and it's necessary."
What really gets him frustrated are demands that seem contradictory or even self-defeating. For instance, he always liked having hawks or owls around, because they help control the mice. But now, those birds are seen as a threat, too.
"I mean, it's frowned on to put up an owl box. The food safety people say, 'Owls poop, too.' OK. But what do they poop? They poop out the mouse that you didn't want in your salad!" Martin says. "Everything we do is conflicting! It seems like we can't do anything right!"
In fact, even some of the people who came up with the new safety guidelines admit that they don't know for sure which of their anti-wildlife rules really do make food safer.
Mark Borman, who's president of Taylor Farms, one of the biggest sellers of fresh leafy greens in the country, says those rules were just the industry's best guess for how they might prevent a repeat of the great spinach disaster of 2006. "When you're faced with an unknown, which is what the industry was faced with six years ago, you throw everything and the kitchen sink at it, right?" he says.
But then you try to get a little smarter, he says. Industry-funded groups and government-funded scientists are currently carrying out research in an effort to figure out which animals really are a serious threat to food safety — and which ones might actually be helpful, because, for instance, they prey on mice.
That research isn't done yet. But Mountjoy, who moved from the USDA to Sustainable Conservation earlier this year, believes that the pendulum is already swinging back, toward greater concern for the environment.
He's been meeting with farmers, environmentalists and state regulators. Together, they're looking for creative ways to manage agriculture in the Salinas Valley so that it's safer but also greener.
"Environmental protection; food safety; economic profit. All of those have to go together," he says.
"Can you have it all?" I ask.
"I think so. I firmly believe so," says Mounjoy.
In fact, he says, the salad-greens industry of the Salinas Valley needs to accomplish all three to survive.
Copyright 2012 National Public Radio. To see more, visit http://www.npr.org/.