The reservoir keeper: monitoring Costa Mar's power margin in a drying season

Tomás Esquivel stands on the concrete lip of the Esperanza reservoir, looking out across the water. The level this morning is 67 percent of capacity—a figure that would have seemed comfortable two months ago, but which now sits squarely in the margin that keeps Costa Mar's power grid stable through the dry season. It is 06:15, and the morning sun is already hot on the water.

Esquivel is the regional operations manager for the Federal Hydro Authority's Costa Mar division. For the past six weeks, as the rainy season has faded and the dry months have begun, he has been watching the reservoir levels with the attention of a ship's captain watching the horizon. The numbers matter not just for Costa Mar, but for three other regions that have begun buying power from the peninsula's dams.

The Federal Hydro Authority sold power to Tierra Verde and Oriente Moderno for the first time in March, a decision made in Meridian to help balance the Federation's energy demand. The contracts run through September. If the reservoirs fall below fifty-five percent, the Authority will have to reduce those exports—a breach that would trigger renegotiation clauses and federal scrutiny.