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June 20, 2023

USGS scientist Molly Wood traveled to Ecuador in April 2023 to advise the Ecuadorian government on sediment and erosion monitoring strategies to support maintenance and sustainability of Ecuador’s largest hydropower facility.

USGS and U.S. Army Corps of Engineers (USACE) scientists and engineers are working with Ecuadorian government officials from the Electric Corporation of Ecuador (CELEC) on strategies for managing sediment and erosion in the Rio Coca basin. USACE, USGS, and other federal agencies are supporting CELEC in their emergency response to rapid sediment erosion and deposition in the Rio Coca after the 2020 collapse of the 144-meter-tall (472-foot) San Rafael waterfall.

The river course changed when the San Rafael waterfall collapsed, causing catastrophic erosion and landslides upstream of the former waterfall site. The erosion is rapidly migrating upstream and threatening approximately $3 billion of Ecuadorian infrastructure, including the Coca Codo Sinclair (CCS) hydropower facility.

The waterfall was located between two features of the CCS hydropower facility along a 61-kilometer reach of the Rio Coca: an upstream dam that diverts water away from the river course into a 25-kilometer tunnel and through a hydropower plant built into the side of a mountain, and the plant’s outlet which discharges water back into the Rio Coca. The upstream dam is at risk of damage from the migrating erosion front, currently less than 8 kilometers away. Downstream, eroded sediment is depositing at the hydropower plant’s outlet, which limits plant operation. Additionally, sediment transported from the river basin headwaters is filling in two reservoirs along the course of CCS facility, limiting hydropower production and sustainability.

CELEC, through their Rio Coca Commission, has requested support from the U.S. government to evaluate the impacts of sediment deposition and erosion on the CCS hydropower facility. The U.S. and Ecuador governments signed a Memorandum of Understanding in 2021 to allow international cooperation on the emergency response. Additional details on the erosion disaster and other USGS support to CELEC are described here.

USGS is working with CELEC and USACE to develop and implement a monitoring program for the river which includes sediment loads, river levels, streamflow, and river and reservoir depths. These data are needed by CELEC for their sustainability assessments of infrastructure and for implementing sediment and erosion management strategies.


Mountainous landscape with green trees, cloudy sky, a river meandering and exposed soil and rock on steep cliffs
Erosion on the Rio Coca upstream of the former San Rafael waterfall site, Ecuador. (Molly Wood, USGS)
Landscape showing stream floodplain and erosion of streambanks, with cloudy sky and forested mountains
Erosion on the Rio Coca and the Rio Loco (foreground), a tributary to the Rio Coca, after a waterfall collapse, Ecuador. (Molly Wood, USGS)
gangway on left leads to a standpipe down to brown stream with forested hills and the brown stream in the background
Sediment and flow monitoring station on the Rio Quijos, Rio Coca watershed, Ecuador. Rio Quijos joins Rio Salado to form Rio Coca upstream of a hydropower facility. The station is jointly operated by the Ecuador National Institute of Meteorology and Hydrology and the Electric Corporation of Ecuador (CELEC). (Molly Wood, USGS)
Reservoir and concrete dam structures and buildings with cloudy sky and forested hillsides
Upstream diversion dam at Coca Codo Sinclair hydropower facility on the Rio Coca, Ecuador. (Molly Wood, USGS)
landscape photograph showing construction vehicles and dark sand-like slopes along a body of brown water, forests, clouds
Sediment deposits at the discharge outlet of the Coca Codo Sinclair hydropower facility on the Rio Coca, Ecuador. (Molly Wood, USGS)
Woman in a blue raincoat and a steeply eroded river valley with forests on top and grey exposed soil and rocks, cloudy sky
Molly Wood at a viewpoint on the Rio Coca, Ecuador, where substantial erosion and landslides have occurred.

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