They also point out that the organic business has transformed what was once a poor area of subsistence farms and where even the low-paying jobs in the tourist hotels and restaurants in nearby Cabo San Lucas have become scarcer during the recession.

To carry the Agriculture Department’s organic label on their produce, farms in the United States and abroad must comply with a long list of standards that prohibit the use of synthetic fertilizers, hormones and pesticides, for example. But the checklist makes few specific demands for what would broadly be called environmental sustainability, even though the 1990 law that created the standards was intended to promote ecological balance and biodiversity as well as soil and water health.

Experts agree that in general organic farms tend to be less damaging to the environment than conventional farms. In the past, however, “organic agriculture used to be sustainable agriculture, but now that is not always the case,” said Michael Bomford, a scientist at Kentucky State University who specializes in sustainable agriculture. He added that intense organic agriculture had also put stress on aquifers in California.

Some organic standard setters are beginning to refine their criteria so that organic products better match their natural ideals. Krav, a major Swedish organic certification program, allows produce grown in greenhouses to carry its “organic” label only if the buildings use at least 80 percent renewable fuel, for example. And last year the Agriculture Department’s National Organic Standards Board revised its rules to require that for an “organic milk” label, cows had to be at least partly fed by grazing in open pastures rather than standing full time in feedlots.

But each decision to narrow the definition of “organic” involves an inevitable tug-of-war among farmers, food producers, supermarkets and environmentalists. While the United States’ regulations for organic certification require that growers use practices that protect water resources, it is hard to define a specific sustainable level of water use for a single farm “because aquifer depletion is the result of many farmers’ overutilizing the resource,” said Miles McEvoy, head of the National Organic Program at the Agriculture Department.