JAKARTA, Indonesia — Standing at his post at a floodgate in the middle of Jakarta, Bejo Santoso says he has seen it all.

He doesn’t mean a lifetime of experiences. He is talking about the variety of man-made waste that floats down the Ciliwung River before it is expunged into a deep bay that a Dutch fleet spotted more than 400 years ago.

Mr. Bejo and dozens of his colleagues stationed at waterways around the city have pulled out refrigerators, televisions, mattresses and furniture. Sometimes they find human corpses — the missing victims of flash floods.

“Every year we find one or two,” said Mr. Bejo, 49, who operates an excavator that removes an estimated 740 cubic feet of garbage and natural debris from the river each day. That’s enough to fill his crew’s truck three times during a shift.