Since pre-Hispanic times the river has been used by the Indians to transport food for commerce. In its early days the city of Valdivia received vegetables from villages via the Cruces River. Before Valdivia became isolated from the rest of the Spanish Empire due to the Arauco War, its main land route (Camino Real in Spanish) to Concepción was drawn following the Cruces river. The river is home to thousands of birds that live in its wetlands. The wetlands were created when the soil that surrounded the river sunk during the Great Chilean Earthquake. The wetlands The most known bird of the place is the Black-necked Swan. In 2004 a CELCOpulp mill opened near San José de la Mariquina, and begun to contaminate the wetlands of the river.