The slow work of taking back the beaches

The dawn light was still thin when Isabel Morales knelt at the tide line on Playa Blanca, sorting through a heap of plastic fragments into mesh bags. Around her, seven other volunteers worked in silence, their hands moving with the practiced efficiency of people who had done this dozens of times before. The pile in front of them—collected over a single high tide—would take two hours to categorize and weigh.

This is the work that does not make headlines. Every month, the Costa Mar Reef Monitoring Network and a coalition of local environmental groups conduct systematic cleanups on eight beaches across the region, recording not just the volume of plastic but its composition, size, and the nutrient levels in the water column offshore. The data feeds into a federal archive and informs policy on everything from tourism permits to agricultural runoff controls in the interior valleys.

In July, the northern beaches—Playa Blanca, Mar del Sur, and the smaller Cove of San Felipe—yielded 847 kilograms of plastic waste, down slightly from June's 920 kilograms but up sharply from the same month last year. Nutrient readings from the monitoring station at Playa Blanca showed phosphorus levels elevated but stable, suggesting that the mangrove-restoration work upstream was beginning to hold the line against agricultural leachate from the interior.

What concerns the crews most is not the volume but the composition. Microplastics—fragments smaller than five millimetres—now account for nearly sixty percent of the collected mass, a shift that accelerated in the past eighteen months. The source remains unclear: some arrives on currents from beyond Costa Mar's waters, some fragments from larger debris breaking down in the sun, and some traces back to local sources that the cleanup data itself is slowly helping to identify.