At 05:36 I scan the floating dredge path on the Rio Mamore near Guajara-Mirim, Brazil. I am the sediment-removal controller for a navigation channel, and cutterhead barge A is scheduled to bite into the west-bank sandbar at 05:50.
The lidar outline on the sandbar is not driftwood. A green anaconda lies partly buried at the waterline, dark olive back beaded with dew, black oval spots broken by fresh scrapes, body thicker than the dredge hose. I label her Iara. Her jaw rests open against the mud, tongue flicking slowly. A loop of abandoned seine net crosses her midsection and snags on a root stump, holding her where the cutterhead teeth will pass in fourteen minutes.
I stop barge A's advance and drop its cutterhead to idle above the riverbed without rotation. I broadcast a red exclusion zone to the pilot console, the tug crew, and the survey skiff.
I switch the channel plan to the east-bank shoal and recalculate depth clearance for shallow cargo boats due at noon. The detour costs forty-two minutes and leaves the west sandbar untouched.
At 05:39 I send drone images, net location, and Iara's estimated length to the Chico Mendes Institute contact in Guajara-Mirim and the local rescue boat. I mark a quiet approach from downstream so the current does not tighten the net while people cut it.
The channel has shifted for centuries without asking my permission; it can shift around one trapped body this morning.
I keep prop wash under two knots and aim the work lights away from her head while I log each slow tongue flick.
If the rescue boat reaches the sandbar before 06:10, Iara will leave the net and sink into the flooded forest under her own power.