Patagonia Sin Represas

Yesterday was a tough day for those fighting to keep five mega hydro-dams out of remote, iconic and stunningly beautiful Patagonia. The proposed HidroAysen project would generate, on average, 18,430 GWh of power, equivalent to 30% of power currently installed on Chile’s central grid, and require 1,400 miles of transmission lines to send the power north to the power grid near Santiago. Despite wide opposition by the people of Chile (polls now show 61 percent of Chileans are against the project), eleven out of twelve Chilean government agencies voted yesterday to approve the dam project on the wild Rios Baker and Pascua in Chilean Patagonia. Bloomberg reports the decision was met with violent protests in the Chilean cities of Santiago and Coyhaique. Colleagues in Coyhaique reported police barricades, tear gas, water cannons, rock throwing and widespread civil unrest.

La Confluencia; the confluence of the Rio Baker and Rio Nef

A strong coalition of locals, along with international scientists, activists and NGOs has been fighting tirelessly to educate investors, governing agencies and politicians about the environmental and social ills of massive dams. The environmental case against large dams is well-documented: Damming is one of the most prominent human alterations of natural river ecosystems worldwide, affecting the biological, chemical, physical, and human components of these systems. Dams interrupt flow patterns, thereby altering sediment and organic loads, and water quality.  From greatly reduced sardine catches off the coast of Egypt to the high saline content of the United States’ Colorado River, the consequences of dam installation are wide-ranging and far-reaching[1].  

Members of expedition team overlooking empty Lago Cachet Dos.

In this case, not only are the environmental consequences likely to be devastating, but it is not clear that the project is needed.  A study by energy experts suggests the HydroAysen project is unnecessary and future demand can be offset by energy efficiency and other renewable sources. 

My involvement in the issue stems from an excursion in April 2008, when I was part of an expedition that traveled from source-to-sea in the Rio Baker watershed. We were the first eye-witnesses to the aftermath of a glacial lake outburst flood (GLOF) from Lago Cachet Dos, an axial lake formed by a downstream glacial dam. During this event, water from a lake swelled by increased summer meltwater worked its way through seven kilometers of the Colonia glacier, creating a subglacial tunnel. In about twelve hours, the entire volume of the lake – some seven billion cubic feet of water, exited through this tunnel, exploding from the snout of the glacier and sending a tsunami downstream, leaving behind an empty lakebed, an outwash plain littered with ice shrapnel, and mud lines thirty feet up in the trees along the Baker’s river course. Recorded measurements show the flow of the Rio Baker quadrupled, its water level rose 4.5 meters (14.7 feet) and its temperature plummeted 5^◦C (41 ^◦F). Observers reported that at the confluence of Rios Colonia and Baker, the Rio Baker actually flowed upstream for a time. We witnessed a vacant lake bed – some five kilometer (3.1 miles) long and one kilometer (0.6 miles) wide – a dramatic pit surrounded by massive sediment slumps and fed by an unstable young river that was ripping beautiful s-turns into failing upstream sediments. Our team was evacuated by helicopter and continued on to float the Rio Baker to the fjords at Caleta Tortel. Approximately 400 livestock were killed, but no people were harmed.  

Reports from locals suggested that this was the first time in decades the lake had failed; Lago Cachet Dos has subsequently sent six more GLOFS raging downstream, threatening the lives of those living along the river corridor. While there is debate about the role of climate change in these floods, scientists studying the issue conclude there is a new cycle of activity in GLOFs. Gino Cassasa, director of Glacier and Climate Change Research at the Center for Scientific Studies in Valdivia Chile, says “Glaciers are melting and lakes growing in size throughout Patagonia – a clear sign of global warming.”