The raucous honking of a cistern truck carrying potable water rouses residents from their homes here each morning, clanging plastic bottles and tin pots in hand.
''When will it stop,'' says 64-year-old Rufina Najera, lugging a yellow 5-gallon pail stained with dirt to the roadside. ``The pineapple companies tell us the water is clean, but the government won't let us drink it.''
Last year, authorities detected small amounts of Bromacil, a pesticide used to thwart insects from pineapple plants, in the local aquifer. Since then, the government has delivered water by truck to nearly 6,000 people.
The crisis has spawned an increasingly volatile movement among residents, who last week blocked the country's principal export artery, Route 32, between the capital of San José and the Caribbean port city of Limón, leaving hundreds of cars and trucks stranded for hours.
More than 60 prominent Costa Rican university scientists and environmental groups joined the chorus of protest in July, citing water pollution and extreme erosion and demanding a moratorium on new pineapple plantations in ``areas of high biodiversity.''
Costa Rica bridges the gap between North and South America, and is said to house 5 percent of the Earth's biodiversity in just .03 percent of its land mass, according to the country's National Biodiversity Institute.
Pineapple companies contend the reports are exaggerated -- and that they've cleaned up their act, and local aquifers.
''Where there are problems, we've worked to solve them,'' says Abel Chaves, president of the country's National Pineapple Producer and Exporter's Chamber. ``If allegations remain, they should be investigated, and if a company is found guilty, it should be charged.''
But many environmentalists and residents say the explosive growth in pineapple production in Costa Rica has outpaced the government's ability to regulate it. Legal loopholes, poor enforcement and lacking public health standards, they say, have placed communities, and ecosystems, at risk.
Pineapple plantations, riding a boom that began when Coral Gables-based fruit company Fresh Del Monte introduced the ''Gold'' pineapple in 1996, have sprawled from nearly 30,000 acres in 2000 to more than 100,000 acres -- outpacing coffee, African palms and bananas as Costa Rica's fastest-growing export crop, according to the country's 2007 State of the Nation report.
Three of every four pineapples consumed in the United States -- 580,000 metric tons -- now originate from Costa Rica, says Alberto Jerardo, of the U.S. Department of Agriculture.
Exports from Costa Rica, meanwhile, have tripled in value with rising demand, from $159 million in 2002 to $505 million in 2007.
But the music stopped in April, when the country's Environmental Tribunal, Costa Rica's highest environmental court, called the burgeoning export industry to task, placing 26 plantations under investigation for abuses ranging from the illegal clearing of forest to water contamination and violation of riverine buffer zones.
The revelations prompted a closer look at industry practices.
Bernardo Vargas, executive director of the pineapple chamber, says his growers responded immediately to concerns, issuing a series of ''social-environmental commitments,'' designed to reduce waste, conserve soil and water and uphold environmental laws.
Many say the nature of large-scale pineapple plantations could make such promises hard to keep.
Jorge Lobo, a University of Costa Rica biologist, says the regional trend toward large-scale industrial monoculture is alarming, particularly in an area so rich in rainfall and biodiversity.
Along the Caribbean slope, just 18 pineapple producers now manage nearly 40,000 acres. In a nearby province to the north, roughly the same acreage is divided among more than 1,000 growers, according to pineapple chamber statistics.
''It's a different kind of agriculture, much more intensive, and more problematic,'' says Lobo, who adds that pineapple -- unlike coffee, another traditional export -- requires direct sunlight for optimal growth and thus, the absence of trees and forest cover, which help prevent erosion in areas of heavy rainfall.
Locals say they are already feeling the effects.
On a recent rainy afternoon, Mario Vargas, a small farmer from La Perla, a Caribbean town now surrounded by vast green swaths of pineapple fields, pointed out a series of creeks and rivers running the color of chocolate near his home. It's proof, he believes, that not enough is being done.
''Before the pineapple arrived, these rivers ran clean,'' he said. ``Why should we be forced to trade our forests and clean water for jobs?''
La Perla's aquifer, explains Vargas, is still safely tucked away in cloud-shrouded mountains, watched over by keel-billed toucans and howler monkeys. But as pineapple plantations continue to expand and move uphill, he and others worry they could be next.
Chaves, of the pineapple chamber, says increasingly paranoid locals have come to blame everything -- water contamination, skin lesions, illnesses -- on pineapple plantations.
''The fact is, there are very few studies that prove these connections,'' he said.
Here, as elsewhere, the pineapple boom caught the country unprepared.
Unlike the United States and Europe, Costa Rica has never had potable water standards for such agro-chemicals as Bromacil, said Health Minister Maria Luisa Avila. The Ministry, she said, drafted a decree last month that would set new limits, a critical first step, she said, to solving the problem.
''We're looking to strike a balance, so that the communities and the pineapple plantations can live in harmony,'' said Avila, who has met with both sides in recent weeks.
Local residents are as quick to blame government regulators as they are the pineapple growers.
As demand for this sweet, vitamin-rich fruit grows in the United States and Europe, many large-scale banana plantations, once the mainstay of the region, have swapped to the more profitable pineapple.
But a loophole in the country's laws exempts most firms operating before 2004 -- the majority of banana-turned-pineapple plantations -- from submitting environmental impact studies.
Gerardo Fuentes, mayor of the canton of Guacimo, says the recent boom has also attracted a sort of ''gold rush'' of newcomers, who buy and clear large tracts of land, then plant pineapple without appropriate permits.
The mayor blames sloppy central government oversight.
Case in point, he said, is that of Setena, the national institution charged with environmental permitting.
Last year, Setena received an environmental impact study from pineapple grower TicoVerde, in which the company referenced pelicans and mangroves (coastal species not found in Guacimo) and squirrel monkeys (a species limited to the central and southern Pacific coast).
Despite such glaring errors, Setena approved the study in June.
Vigilant locals, who have learned to scour government documents, cried foul. The municipality declared a moratorium on new pineapple seeding and filed a lawsuit against Setena, demanding TicoVerde's environmental permits be revoked.
Setena officials did not reply to repeated phone calls and requests for interviews by press time.
Until such issues are clarified, environmentalists say they will insist on a moratorium on new pineapple seeding -- and a zero-tolerance policy for agro-chemicals in their water supplies.
Lourdes Brenes, director of Foro Emaus, an umbrella organization for 22 community action groups that has spearheaded the fight, says the idea is not to shut down the pineapple industry.
''We simply want them to obey the law, and the government to enforce it,'' she said.