Pilcomayo is a department in the Argentine province of Formosa. Its capital is Clorinda, the second most populous city in the province. Pilcomayo has a surface of 5,342 km2 and a population of 78,114 according to the . Other communities in Pilcomayo include Laguna Blanca, Laguna Naick Neck, Riacho He-Hé and Siete Palmas. The Pilcomayo River National Park (Parque Nacional Río Pilcomayo) is about 45 kilometers west of Clorinda, crossed by the Pilcomayo River.