Cristina Ye Wang, c.ye@alumnos.upm.es
The Klamath is a river more than 400 kilometres long. It is located in the United States, and crosses the states of Oregon and California, flowing into the Pacific Ocean. Historically, the indigenous people that lived on the shores subsisted on fish populations. In addition, the river provided water for irrigation and drinking water supply. However, at the beginning of the 20th century, advances in hydroelectric energy led to the construction of numerous dams, including the Klamath River dams.
The Iron Gate, Copco 1, Copco 2 and J.C. Boyle dams are four of the six dams built on the Klamath River. These dams have been blamed for causing declines in the populations of several species of salmon and trout, as well as deteriorating water quality in the river.
Figure 1. Map of Klamath River highlighting the dams that will be removed (California Water Science Center, 2022).
Although these dams provided hydroelectric power to communities in the area, they also greatly affected fish populations. Aside from making migration more difficult, the dams altered the natural temperature of the river, increasing the mortality of adult fish and reducing the survival capacity of young fish. As a result, the river’s salmon population has reduced to just 10% of its initial size, and is now an endangered species. This not only affects indigenous communities, but also alters the entire food chain of the fluvial habitat.
For years, different environmental organizations and indigenous communities have fought for the removal of the dams. The company that operated the dams, PacifiCorp, admitted that demolition would be cheaper than building fish ladders, adapting them to new fish passage legislation, and maintaining water quality. Moreover, for years the dams had been used exclusively to generate hydroelectric energy and had no real use for water supply.
Finally, in 2016, the Klamath River Renewal Corporation (KRRC) was created. This organization is in charge of carrying out the dam removal and river restoration project. In 2022, the Federal Energy Regulatory Commission (FERC) of the United States authorized the demolition of the four dams, with a budget of about 450 million USD. This operation would cover about 520 km of river. The operation began in 2023. At the end of that year, the smallest dam out of the four, Copco 1, was dredged and demolished. The project is expected to be completed this year, 2024.
However, the project not only covers the removal of the dam, but must also carry out the restoration of the reservoirs. When a dam is built, the natural state of the river is altered, and one of the most important factors is the accumulation of sediment in the reservoir. After the first dam was demolished, approximately 2.3 million tons of sediment were released into the river. This caused the water quality to greatly deteriorate. There were even numerous locals who noticed an increase in dead fish and animals trapped in the mud that had formed in the riverbed. Anyhow, other cases of dam demolitions indicate that this is a necessary process for the river to return to its original natural state.
Figure 2. Copco 1 Dam reservoir after the dredging and removal of the dam (Klamath River Renewal Corporation, 2024).
The KRRC also has a revegetation and soil stabilization plan, which includes planting native grasses throughout the reservoirs. In addition, trees and shrubs will also be planted in the riparian zone to prevent excessive sedimentation and help the recovery of the habitat. All areas will be monitored for years to ensure that the revegetation is successful.
Likewise, there is also a program focused on monitoring water quality, both before, during and after the dredging and demolitions. The plan covers taking real-time measurements of different parameters such as temperature, dissolved oxygen and suspended solids. The goal is to ensure that water quality laws are met, as well as maintain adequate living conditions for the fish.
In addition to ecological and technical considerations, the KRRC also had to take into consideration how to protect the communities settled on the banks of the river. With the demolition of the dams there is a new risk of flooding that must be addressed. Although the dams were hardly useful for flood control, it has been estimated that the removal will increase the flood level by 40 centimeters for a flood with a return period of 100 years. This will affect a small number of homes, and the KRRC has already financially compensated those affected.
The case of dam removal on the Klamath River is not unique. Throughout 2022, 65 dams were demolished in the United States, and in 2023, 487 dams were demolished in Europe. In recent years, there has been a growing trend in favor of the removal of this type of infrastructure. Defenders claim that many dams are obsolete and should be demolished, since they have no real use and only degrade the natural habitat in addition to potentially collapsing, causing fatal accidents.
Bibliography:
Beldon, C. (2023). Why America is Removing These Dams. Available at: https://www.theb1m.com/video/klamath-worlds-largest-dam-removal [Consulted 15-04-2024].
Novo, C. (2020). “Estados Unidos prepara el mayor proyecto de demolición de presas hasta la fecha”. iagua, June 10th. Available at: https://www.iagua.es/noticias/redaccion-iagua/estados-unidos-prepara-mayor-proyecto-demolicion-presas-fecha [Consulted 15-04-2024].
ASERSAgua (2018). Supresión de cuatro presas en el río Klamath. Available at: https://www.asersagua.es/supresion-de-cuatro-presas-en-el-rio-klamath/ [Consulted 29-04-2024].
Dam Removal Europe (2024). New Report: Dam Removal Movement Breaks Barriers and Records. Available at: https://damremoval.eu/dre-report-2023/ [Consulted 02-05-2024].
Klamath River Renewal (2017). Klamath River Renewal Corporation. Available at: https://klamathrenewal.org [Consulted 15-04-2017].
