In 2004 and 2005 thousands of Black-necked Swans in the Carlos Anwandter Nature Sanctuary in Chile died or migrated away following major contamination by a newly opened CELCO pulp mill located near the city of Mariquina and Cruces River which feeds the wetlands. By August 2005, the birds in the Sanctuary had been "wiped out"; only 4 birds could be observed from a population formerly estimated at 5,000 birds. Autopsies on dead swans attributed the deaths to high levels of iron and other metals polluting the water. The company had been dumping dioxins and heavy metals into the river illegally from a wastetube that had not been approved by the authorities. The plant was closed in 2005 after the company lawyers reportedly produced a misleading environmental study regarding pollution on the Cruces River. The scandal prompted Celco's chief executive to resign in June 2005 and the company to pledge to adopt cleaner technologies. The plant reopened two months later at limited production capacity. Even in 2006 the Latin American water tribunal recommended to close down the mill. In July 2007 CELCO agreed to pay $614 millions Chilean Pesos to Valdivian tourism companies to avoid legal actions for supposed loses of the tourism sector of Valdivia due to contamination of Carlos Anwandter Nature Sanctuary. In a document signed the tourism companies CELCO was exempted from all responsibility involving the contamination of Cruces River. CELCO also promised to pay $2 million monthly each of the coming 3 years to promote tourism.