Page "Geography of Paraguay" Paragraph 26

Paraguay's third largest river, the Pilcomayo River, flows into the Paraguay River near Asunción after demarcating the entire border between the Chaco region and Argentina.

During most of its course, the river is sluggish and marshy, although small craft can navigate its lower reaches.

When the Pilcomayo River overflows its low banks, it feeds the Patiño Estuary ( Estero Patiño ).