Community Blog

Call for Contributors: Run-of-the-River Hydropower Dams

Calling on researchers with particular knowledge and experience about so-called “run-of-the-river” dams to collaborate with Dr. Ian Baird and Dam Watch International on developing an in-depth article about how “run-of-the-river” hydropower dams have been promoted. Please read on below for more information.

Cover photo: the Pak Mun dam, on the Mun River in Northeastern Thailand

For a few decades now, the hydropower dam industry has been doing various things to try to improve their reputation, as hydropower dams all over the world have been shown to cause an array of serious social and environmental impacts (WCD 2000). For example, more emphasis has been put on describing energy generated from dams as “renewable”, “green power”, and “climate-friendly” (Baird and Green 2020).

One key way that hydropower dams have been greenwashed is through characterizing some as “run-of-the-river”. This terminology is intended to give people the impression that a river’s flow is not being altered, and that it is continuing to flow as before, and thus such projects have few if any social and environmental impacts (Roberts 1995).

The fish ladder on the Pak Mun Dam, which has been shown to not facilitate many fish to migration upstream past the dam. Photo by Ian Baird.

The reality, however, is often starkly different. For example, one of the most destructive dams ever built in the Mekong River Basin is the Pak Mun Dam, built on the lower Mun River in northeastern Thailand. It was characterized as a run-of-the-river dam, as it is only 17 metres high and has a capacity of 136 MW. However, in reality it caused quite serious social and environmental impacts by blocking important fish migrations during different seasons (Roberts 1993; 1995; 2001). The severe impacts of the project were well documented by the World Commission on Dams (WCD 2000), and are continuing up to now (Baird et al. 2020a; b; Green and Baird 2020).


In fact, the technical definition of a “run-of-the-river” dam is that it does not maintain any or much active storage of water like other projects with large reservoirs. However, these dams can still seriously alter water flows, affect water quality, and dramatically change ecologies. They can greatly negatively impact the livelihoods of people dependent on them. For example, the Theun-Hinboun Hydropower Project in Laos, also in the Mekong River Basin, includes a dam in the Theun River in Central Laos. A large portion of the water in the Theun River is then diverted into a canal to generate power, before being diverted into another river called the Hinboun River.

The Theun-Hinboun Dam in Central Laos is considered to be a “transbasin run-of-the-river project”. Photo by Ian Baird.

The dam has caused serious social and environmental impacts downstream of the dam in the Theun River, since the river has largely been diverted from its original riverbed. It has also caused serious erosion and water quality problems downstream in the Hinboun River, since the amount of water in the Hinboun has increased dramatically. To maximize power generation, this water is being released in certain seasons and particular times of the day (Barney 2007; Whitington 2018). The developers referred to the dam as a “trans-basin run-of-the-river hydropower project”, even though the river does not even flow into its original river basin anymore. Again, the term was used to try to downplay the project’s negative impacts.


Some have the incorrect impression that run-of-the-river dams tend to not be high dams or large projects, and that they invariably cause less impacts than dams with larger reservoirs. However, the Peace River Canyon Dam in Northeastern British Columbia, Canada is 50-metres high, but despite being a high dam, it is still considered to be a “run-of-the-river” project (Baird et al. 2021). In addition, some run-of-the-river dams are actively massive. For example, on a tributary of the Amazon River in Brazil, the Madeira River, there are two large dams, the Santo Antônio and the Jirau dams, which have greatly altered the ecologies of the rivers. They have installed capacities of 3,568 and 3,750 MW respectively (Almeida et al. 2020; Baird et al. 2021). Finally, the Lower Sesan 2 dam, in northeastern Cambodia is considered to be a “run-of-the-river” project, but was assessed as being more likely to cause more serious impacts to fish migrations than any other large dam planned for the Mekong River Basin (Ziv et al. 2012; Soukhaphon et al. 2021). Thus, some of the most destructive dam projects are actually run-of-the-river dams.

I am looking for other researchers with particular knowledge and experience about so-called “run-of-the-river” dams to collaborate with me and Dam Watch International on developing an in-depth article about how “run-of-the-river” hydropower dams have been promoted, and also about how they have caused serious social and environmental impacts in various river basins around the world, and in different contexts.

If you have an interest in collaborating on this joint project on investigating and documenting the impacts and ways of promoting “run-of-the-river” dams, please contact me as soon as possible, and no later than September 15, 2022. Once we have developed a list of collaborators, we will organize a meeting to decide how best to proceed.

Please contact:

Dr. Ian Baird

Professor of Geography

University of Wisconsin-Madison



Almeida, R.M., S.K. Hamilton et al. 2020. Hydropeaking operations of two run-of-river mega-dams alter downstream hydrology of the largest Amazon tributary. Front Environ Sci.

Baird, Ian G. and W. Nathan Green 2020. The Clean Development Mechanism and large dam development: Contradictions associated with climate financing in Cambodia. Climatic Change 161: 365–383.

Baird, Ian G., Kanokwan Manorom, Aurore Phenow and Sirasak Gaja-Svasti 2020. Opening the gates of the Pak Mun Dam: Fish migrations, domestic water supply, irrigation projects and politics. Water Alternatives: An Interdisciplinary Journal on Water, Politics and Development 13(1): 141-159.

Baird, Ian G., Kanokwan Manorom, Aurore Phenow and Sirisak Gaja-Svasti 2020. What about the tributaries of the tributaries? Fish migrations, fisheries, dams and fishers’ knowledge in northeastern Thailand. International Journal of Water Resources Development 36(1): 170-199.

Baird, Ian G., Renato Silvano, Brenda Parlee, Mark Poesch, Bruce Maclean, Art Napoleon, Melody Lepine and Gustavo Hallwass 2021. The downstream impacts of hydropower dams and indigenous and local knowledge: Examples from the Peace-Athabasca, Mekong and Amazon. Environmental Management 67(4): 682-696.

Barney, Keith 2007. Power, progress and impoverishment: Plantations, hydropower, ecological change and rural transformation in Hinboun District, Lao PDR. Toronto: York University Centre for Asian Research (YCAR) Working Paper No. 1.

Green, W. Nathan and Ian G. Baird 2020. The contentious politics of hydropower dam impact assessments in the Mekong River Basin. Political Geography 83: 102272.

Roberts, Tyson R. 1993. Just another dammed river? Negative impacts of Pak Mun Dam on fishes of the Mekong Basin. Natural History Bulletin of the Siam Society 41: 105-133.

Roberts, Tyson R. 1995. Mekong mainstream hydropower dams: Run-of-the-River or ruin-of-the-river? Natural History Bulletin of the Siam Society 43: 9-19.

Roberts, Tyson R. 2001. On the river of no returns: Thailandʼs Pak Mun Dam and its fish ladder. Natural History Bulletin of the Siam Society 49: 189-230.

Soukhaphon, Akarath, Ian G. Baird and Zeb Hogan 2021. Hydropower dams and impacts in the Mekong River Basin: A Review. Water 13, 265.

Whitington, Jerome 2018. Anthropogenic Rivers: The Production of Uncertainty in Lao Hydropower. Ithaca, NY: Cornell University Press, 2018. xvi + 266.

WCD (World Commission on Dams) 2000. Dams and Development: A New Framework for Decision-Making. London: Earthscan Publications.

Ziv, G., E. Baran, S. Nam, I. Rodríguez-Iturbe, and S.A. Levin 2012. Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin. Proc. Natl. Acad. Sci