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.