Too much water for the wetlandsBogota, Colombia: Lake Cocha is at the heart of the greatest wetland system in the Colombian Andes. In the south-west of Colombia, on the border with Ecuador, the lake is the source of the Guamues river, which crosses the four lowest paramos in the world.
Paramos, or high-altitude grasslands, are normally found above 3,000 metres, but these in Colombia are just 2,800 metres above sea level. Separated from each other by the river and by patches of Andean forest, they contain almost 50 per cent of South American paramos bird species, as well as rare plants such as Espeletia cochensis, a rosette-looking species found nowhere else in the world. But today this globally significant area is threatened by an ambitious plan to construct a dam and power station on the Guamues. The dam would be built to the south of Lake Cocha, some eight kilometres along the river. Twenty- eight cubic metres of water per second would be channelled from the lake to guarantee future supplies for the nearby city of Pasto.
But in order to make the most of the additional flood, a hydro-electric power plant would be built on a natural waterfall. Promoters of the project propose to generate approximately 1,000 megawatts of power (equal to 60% of the energy currently used in Colombia). A very small part of this energy would be used to increase power capacity in Pasto and surrounding areas, with the surplus being sold to other parts of Colombia and to Ecuador.
This Multi-purpose Guamues Project - PMG in Spanish - is now beginning the legal process required to obtain an environmental licence from the Colombian government. But fears are spreading about the impact of the scheme on the valuable ecosystem of Lake Cocha.
Experts say that not only would it destroy much of the unique paramos, but it would also remove a large slice of Andean forest and parts of private nature reserves created by farmers in the region. It would also affect the Patia river watershed and reduce the flow of the Guamues and Putumayo rivers, the latter being one of the largest tributaries of the Amazon.
Engineer Francisco Arevalo, a PMG supporter, has already made clear that the scheme will flood 200 hectares of riverbanks, which would destroy about 10 per cent of paramos adjacent to the wetland. But preliminary analysis, made with assistance from the local University of Narino, suggests the area flooded will be closer to 900 hectares.
Paramos are considered water "industries" because they have the capacity to regulate this valuable resource. Typical paramos plants - espeletia, lichens and moss - act as sponges, absorbing large amounts of water in winter, then slowly releasing it to guarantee humidity even during the summer. Moss, for example, can store up to 40 times its weight in water. So it is not surprising that the sources of many Colombian rivers are located in or close to paramos.
Even the smallest flood generated by PMG will damage the water regulation capacity of the paramos. In addition, flooding would have a serious impact on the region's bird life, according to biologist John Jairo Calderon of the Association for Campesino Development (ADC), which is working in the area with the conservation organization, WWF. "Some bird species rely solely on these paramos," he says.
Calderon is also concerned about the extraction of water from the lake, which would enormously reduce the volume of the Guamues river and decrease its flow into the Putumayo - possibly affecting its navigability. The danger to the Pasto river would be an increase in the floods that already affect riparian communities. Meanwhile, the patches of Andean forest that would also be flooded are also crucial to many birds, such as the spectacled whitestart and masked flowerpiercer, which live alternately in the paramos and the rainforest.
For nearly 20 years, the area has been the focus of important conservation efforts by local communities, who have substituted deforestation and vegetable coal extraction for sustainable productive activities. Since 1993, ADC and WWF's Colombia office have worked together to offer technical and financial assistance to many of these efforts. There are about 3,000 hectares of land close to Lake Cocha containing some 35 private nature reserves, and the ADC's Belisario Cepeda says up to 15 of them would be affected by the PMG scheme.
Mary Lou Higgins, of WWF Colombia, points out that an environmentally viable alternative for the project would be to eliminate the power supply element. That would reduce the area to be flooded, and instead of the extraction of 28 cubic metres of water per second from Lake Cocha only three cubic metres per second would be necessary.
With this in mind, WWF Colombia is working with other organizations in the region to complete biological studies to emphasise the significance of the Lake Cocha ecosystem and to propose less damaging alternatives to PMG. The hope is that an environmentally acceptable scheme can be developed and that the Colombian government will take the opportunity of the seventh conference of the parties to the Ramsar Convention on Wetlands in May to declare Lake Cocha a Ramsar site.
* Vanessa Diago is Communications Officer at WWF Colombia