Bane or Boon?
The developers counter that their projects will help maintain the region's ecological equilibrium—or even improve it.
Architect Ari Nieto Vélez, developer of the larger project, known as Tambora, said the site was designed with eco-tourists in mind.
Tambora would go up on a 1,684-acre (681-hectare) parcel of land that directly abuts the reserve. It includes a hotel with a hundred rooms, an 18-hole golf course, and residential lots.
According to Nieto Vélez, the project will require 390 million gallons (1.5 million cubic meters) of freshwater a year, but nearby water resources are ample, developers say.
In a study released in February, however, Castillo and other members of the technical panel noted that the local water resources are not sufficient to meet Tambora's needs.
"The Chamela Arroyo [creek] is the water source for various vertebrate species and constitutes a fundamental habitat for survival during the dry season," the study said. "The arroyo's affectation ... would have a strong impact on the integrity of the Chamela-Cuixmala Biosphere Reserve."
The other project, Careyitos, would sit less than a mile (1.6 kilometers) from the reserve.
The 634-acre (257-hectare) site—now home to mangroves and a section of beach where sea turtles nest—will include 198 homes and 255 hotel rooms and villas.
Jose Manuel Bosoms, the developer of Careyitos, also defended his project as a model of ecotourism.
As much as 88 percent of the site will be preserved for conservation purposes, Bosoms said, and his company will work to maintain biological corridors between the reserve and the ocean.
Bosoms also pointed out that a significant amount of habitat fragmentation has already occurred around the reserve from deforestation by local residents, and that his project will help preserve key habitat.
Both projects, though small compared to many luxury resorts under construction elsewhere along Mexico's coasts, follow a pattern of golf-oriented development that stretches up through Mexico's arid northwestern region into the Baja California Peninsula.
Despite the promises of environmental protection, the two projects have drawn a flurry of protest in Mexico.
The heirs of Sir James Goldsmith, a Franco-British tycoon, are among the sharpest critics of the planned developments. Goldsmith donated land in 1987 that, combined with gifts from other affluent landowners in the 1970s, ultimately led to the creation of the Chamela-Cuixmala reserve.
In July more than 700 academics and researchers affiliated with the Association for Tropical Biology and Conservation called on the Mexican government to cancel the projects' permits and prohibit further tourism development in the area.
And scientists are urging Mexico's environment and natural resources secretariat, Semarnat, not to grant land use permits this month, even though the agency has signed off on environmental impact reports for the projects.
Developers will be unable to begin construction until they receive the permits.
Mauricio Limón Aguirre, the deputy director for environmental protection at Semarnat, said his agency is wrestling with new information provided by scientists on the potential impact of the developments on the reserve.
Semarnat authorized the projects' environmental impact reports late last year, and no formal objections to the projects had been submitted during the public comment period.
The technical panel's report arrived late in the process, but has the potential to affect the approval of the second set of permits, according to Limón Aguirre.
Water is a serious issue of concern, he said, but local water resources are threatened by more than just the developments.
"This is a water-stressed zone, but the local communities are also polluting and misusing the scarce water resources by throwing their wastes in the ocean and streams," he said.
"At least in a development you can impose restrictions. It's harder to do that in the local communities."
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