Destruction of Puerto Rico's Karst Landscape

Puerto Rico's karst landscape—covering approximately 244,285 hectares or 27.5% of the island's surface—is one of the most biologically rich and geologically unique ecosystems in the Caribbean. The Northern Limestone Zone, running from Aguada to Loíza, accounts for 90% of the karst region and contains the island's most extensive forest canopy cover.

The karst holds 1,300 species of plants and animals, including 30 federally listed threatened and endangered species. Its mogotes—steep-sided residual limestone hills created over millions of years of dissolution—are geological formations found in only a handful of places worldwide. The North Coast Karst Aquifer System is Puerto Rico's most productive aquifer but also its most vulnerable, as porous limestone transmits contamination rapidly.

Since the mid-20th century, limestone quarrying for cement production, construction aggregate, and road building has been systematically destroying mogote formations. The calcium carbonate content of 85-95% in the formations makes them commercially valuable. Quarry de-watering and water table decline are the two key factors inducing subsidence sinkholes—sudden ground collapses that threaten homes and infrastructure.

The community organization Ciudadanos del Karso (Citizens of the Karst) has advocated for protection of these formations, fighting quarrying permits and development that threatens both the geological heritage and the aquifer. Their work represents a local environmental justice movement defending a landscape that most Puerto Ricans depend on for drinking water.

Municipalities most affected include Arecibo, Barceloneta, Vega Baja, Vega Alta, Toa Baja, Hatillo, and Manatí—the same communities impacted by pharmaceutical groundwater contamination.