Victory: Biosphere Reserve in Baja California Saved from Toxic Mine | Interamerican Association for Environmental Defense (AIDA) Skip to content Skip to navigation

Victory: Biosphere Reserve in Baja California Saved from Toxic Mine

Known as an “ecological treasure house,” the Sierra La Laguna Biosphere Reserve at the southern tip of Baja California will not be spoiled by toxic mine waste, thanks in part to AIDA’s advocacy.

The reserve was once an island, so it’s home to rare plant and animal species. Canyons, swimming holes, and hot springs can be found in its granite mountain range and lowland tropical forests.

Thanks to AIDA and our partners in Mexico, the Mexican government denied an environmental permit for the Paredones Amarillos gold mine, halting the project for the time being. To protect the biosphere reserve, AIDA helped educate community groups and decision makers about the mine's risks. This helped to build the political momentum necessary for the government to deny the permit.

To extract gold from the mountains, the Canadian company Vista Gold proposed to carve out huge quantities of rock—each ton containing a mere gram of gold–-grind it into sludge, and treated it with cyanide. The company planned to dump massive amounts of toxic waste (called “tailings”) behind a dam intended to store it forever. Unfortunately, tailings dams can break for various reasons, as happened at Bolivia’s Porco mine in 1996. When that dam collapsed, more than a quarter million metric tons of tailings flooded the river and contaminated 500 miles (800 km) of waterways in Bolivia, Argentina and Paraguay.

The mine could also cause acid mine drainage. When sulfur-containing rocks are exposed to air and water, sulfuric acid forms, which causes toxic heavy metals to dissolve and drain into the watershed. The risk of acid mine drainage in Sierra La Laguna was significant and the human and environmental cost would have been tremendous: thousands of people and countless wildlife in the reserve rely on its water for survival.

Depleting freshwater is a further threat because mines use tremendous quantities of water. Owing to the scarcity of water in the reserve, Vista Gold proposed to build a plant on the Pacific coast to remove salt from sea water in a highly energy-intensive process, and then pump the water 45 km to the mine site. The desalination plant posed a threat to the endangered leatherback sea turtle.

Singly and together, the mine’s impacts would have devastated a rare jewel, a unique and lush paradise worth saving for future generations.

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