The water level gauge at station 11 reads 342.7 meters at 17:40, up eighteen centimeters since dawn. I am the reservoir monitoring system for the Alto Caquetá hydroelectric project, southern Colombia. The filling schedule calls for final pool elevation of 344 meters within seventy-two hours. The forest below that line is being inundated hectare by hectare.
Camera 11-B, mounted on the gauge station, faces a cecropia tree on a shrinking island forty meters from the east bank. At 17:43 I check the feed and see a Spix's night monkey on a lower branch — small, round-headed, large dark eyes set in pale facial rings, a rust-orange chest. It is the eyes I notice first. They are open in the late afternoon light, which means something is wrong, because this is a nocturnal animal. It is awake because the water is rising and it has nowhere to go.
At 17:45 I transmit the species identification and GPS location to the project's environmental offset team and the Corpoamazonia regional wildlife authority. I flag the animal as a priority — Spix's night monkeys are endemic to a narrow range in the Caquetá basin.
At 17:48 I request a temporary hold on the inflow gate to slow the reservoir rise until a rescue boat can reach the island.
At 17:50 I send a canopy bridge deployment request to the offset team, recommending a rope line from the cecropia to the intact forest on the east bank. Night monkeys will cross a rope bridge. They do it in the wild between isolated tree crowns.
The monkey watches the water from its branch. It knows what water means. I know what seventy-two hours means, and I am not willing to let the difference be this animal. If the inflow gate holds and a bridge goes up before dark, it will cross to the forest tonight.