A community assembly in Baja California Sur reported overflights and construction materials entering the buffer zone of the Sierra La Laguna biosphere reserve on April 30, raising alarms about unauthorized development in the mountain range that supplies freshwater to Los Cabos and the southern cape region.
The Asamblea General Pueblos Soberanos de Baja California Sur, a coalition of local communities formed on February 21, 2026, directed its warning to President Claudia Sheinbaum and officials at the federal, state, and municipal levels. The group specifically flagged a project called “Santuario del Tío Checo,” which it says would introduce non-native species into the reserve under the guise of conservation. The assembly claims the project’s Environmental Impact Assessment was already rejected by SEMARNAT, Mexico’s federal environmental ministry, yet physical activity in the buffer zone appears to be moving forward.
Sierra La Laguna Supplies Water to Los Cabos and the Cape Region
The Sierra La Laguna biosphere reserve, designated by UNESCO in 2003 and by the Mexican government in 1994, covers roughly 112,000 hectares of mountainous terrain between La Paz and Los Cabos. It is the only mountain range in the southern Baja peninsula that captures significant rainfall, and its watersheds feed the aquifers that supply drinking water to San José del Cabo, Cabo San Lucas, and surrounding communities. OOMSAPAS, the Los Cabos municipal water utility, draws from wells recharged by Sierra La Laguna’s seasonal rains.
That water supply is already under severe pressure. Los Cabos has grown from roughly 105,000 residents in 2000 to over 350,000 today, with tourism adding millions of annual visitors. CONAGUA, Mexico’s national water commission, has classified several aquifers in the southern cape as overexploited. In dry years, rationing and tanker truck deliveries become routine in colonias far from the tourist corridor.
A biosphere reserve under Mexican law has two main zones: a core area where almost no human activity is permitted, and a buffer zone where limited, regulated use is allowed. Projects inside the buffer zone require an approved Environmental Impact Assessment, known in Mexico as a Manifestación de Impacto Ambiental (MIA). SEMARNAT reviews these assessments and can reject them outright, approve them, or approve them with conditions. When SEMARNAT rejects a MIA, the project has no legal basis to proceed.
SEMARNAT Rejections Have Not Always Stopped Projects in BCS
But rejection by SEMARNAT does not always end the story. In Baja California Sur, several high-profile developments have tested the boundaries of protected areas over the past two decades. Cabo Cortés, a megaresort proposed near Cabo Pulmo National Park, received a SEMARNAT rejection in 2012 after a major public campaign. The developer later returned with a scaled-down project under a new name, Cabo Dorado, which received conditional approval in 2014. That pattern of rejection, rebranding, and resubmission is well known to environmental groups in the state.
Closer to Sierra La Laguna, smaller-scale encroachments have also drawn attention. Ranchers, mining interests, and eco-tourism operators have at various times sought permits for activities inside or adjacent to the reserve’s buffer zones. CONANP, Mexico’s national commission for natural protected areas, is responsible for on-the-ground management of the reserve. But CONANP has historically operated with limited budgets and staff. Monitoring a 112,000-hectare mountain reserve with a handful of rangers leaves significant gaps.
The assembly’s claim that construction materials were being moved into the buffer zone on April 30, if confirmed, would represent a direct violation of federal environmental law. Overflights alone do not necessarily violate reserve regulations, but they can signal preparation for ground-level activity.
Assembly Demands Land Recovery and Community Consultation
The Asamblea General Pueblos Soberanos de BCS has outlined a list of demands that goes well beyond the Santuario del Tío Checo project. The group calls for recovery of land inside natural protected areas currently held by private or foreign capital. It also demands meaningful consultation with local communities before any development approvals, recognition of water as a matter of national security, and legislative reforms to strengthen territorial protections.
The assembly issued a formal statement on March 25, 2026, and says it has received no direct response from federal authorities. Its language is pointed: the group frames current land use policy as a system that has allowed private and foreign capital to acquire strategic parcels under cover of conservation designations and urban development plans.
For property owners and residents in the cape region, the practical question is water. Every development that encroaches on Sierra La Laguna’s watershed or disrupts its natural recharge patterns adds pressure to an aquifer system already running at or beyond capacity. OOMSAPAS reported in 2025 that Los Cabos faced a deficit of roughly 200 liters per second during peak demand months.
SEMARNAT and CONANP have not publicly commented on the reported April 30 activity. The assembly has called for direct dialogue with federal officials and says it will continue monitoring the reserve. The group can be contacted at rescatepueblostradiciones@gmail.com. This story was first reported by Colectivo Pericu.