Pilcomayo River to Be Saved from Ruin

Work is under way to design a management plan to recover the clogged watershed of the Pilcomayo River, which extends across 270,000 square km in Argentina, Bolivia and Paraguay.

TARIJA, Bolivia - A management plan to take effect in 2008 could save from collapse the contaminated and clogged Pilcomayo River watershed, which extends over 270,000 square km of Argentina, Bolivia and Paraguay.

The Pilcomayo begins in the foothills of the Andes Mountains, between the southwestern Bolivian departments of Oruro and Potosí, and flows south through Chuquisaca and Tarija departments, passing through the Argentine province of Formosa, and into the Paraguay River near Asunción.

The governments of the three South American countries involved, with financial support from the European Union, formed a commission to draw up a Master Plan for recovering the Pilcomayo basin.

The commission's technicians have determined that ''during the past centuries both climate conditions and intervention by humans have caused the Pilcomayo River to become what is considered today a natural resource beyond human control.''

They have been conducting studies since 2002 and are slated to finish when the plan begins implementation in 2008, with the aim of recovering the watershed and promoting sustainable development in this trinational zone over the subsequent 17 years, until 2025.

The trinational commission headquarters are in Asunción and the headquarters for the project operations are in the southern Bolivian city of Tarija, with Argentina and the EU as co-directors.

The river basin is home to approximately 1.5 million people: one million in Bolivia, 300,000 in Argentina, and 200,000 in Paraguay.

''High contamination is found mainly in the upper watershed (Bolivia), where since Spanish colonial times there has been mining (silver, tin, zinc, lead, arsenic and antimony),'' Jorge O'Connor, executive director of the National Commission of the Pilcomayo and Bermejo Rivers, told Tierramérica.

At the beginning of the new century, 32 ore processing plants in Potosí were responsible for the contamination. The Bolivian government shut down the 19 worst polluters in April.

Runoff of toxic waste from the mining industry and the sediment from erosion on the Bolivian side have negative impacts on the natural course of the Pilcomayo, whose route changes frequently and whose flow volume diminishes dramatically by the time it reaches the lower watershed, leaving Argentine and Paraguayan wetlands without water to replenish them.

The experts consider the sediment production process to be beyond human control: 60 million cubic meters per year that lead to abrupt changes in the flow, from 3,000 or more cubic meters per second to lows of just three cubic meters.

This has caused blockage and reduction of the Pilcomayo at an average of 5.7 km per year between 1935 and 1998, leaving on the verge of collapse the ecosystems of the agricultural, livestock and aquaculture zone of the three countries and the wetlands of the lower watershed.

Erosion and sedimentation associated with the changes in the river's route cause disastrous floods and drought, with major losses for local crops and livestock.

The contamination of the water has hit the fishing industry hard. Some 350,000 people work in the sector that produces some 800 tons of fish a year, with ''enormous economic losses, a decline in the already precarious living conditions of the population, and the destruction of biodiversity,'' says O'Connor.

There are some 60 fish species recorded in the upper and lower Pilcomayo, but just a few are sought by fisherfolk, such as the sábalo (various species, including the Prochilodus platensis, Curimatorbis platanus and Curimata gilberti), dorado (Salminus maxillosus) and surubí (Pseudoplatystoma coruscans and Pseudoplatystoma fasciatum).

All along the river, the diversity of bird species varies. In La Puna there some 240 species, in the arid inter-Andean valleys 520, in the Tucuman-Bolivian forest 407, and in the Chaco there are 403 bird species.

The Pilcomayo basin's amphibians and reptiles have not yet been quantified, but experts consider the river to be one of the richest ecosystems in these species. Meanwhile, there are more than 150 mammal species, with the Andean portion of the river being home to the greatest number.

The economic and social impact in the three countries -- preliminary data is expected next year -- is complex and vast, according to Marcelo Trigo, head of the Pilcomayo River project.

The South American and European technicians entrusted with the Master Plan's studies propose the immediate construction of dams to regulate the flow of the river at five points in Bolivia, rehabilitation of field stations to measure water and sediment levels, and development of simulations of the watershed's functioning, as well as feasibility studies of irrigation with the regulation of the dams.

Also on the agenda are a pilot project for recovering farmland, recovery of wetlands in Argentina and Paraguay, and promotion of a binational nature reserve between those two countries with the Estrella and Tifunque marshes.

The local populations living in the watershed in the three countries are participating in the preliminary studies and projects. According to the project directors, ''the cultural contexts of each one of the groups that inhabit the zone (are respected and encouraged) so that they become the plan's protagonists.''

* José Luis Alcázar is a Tierramérica contributor.