Editing Hydropower (section)

== Disadvantages and limitations ==
{{Main|Hydroelectricity#Disadvantages|Renewable energy debate#Hydroelectricity}}
Some disadvantages of hydropower have been identified. [[Dam failure]]s can have catastrophic effects, including loss of life, property and pollution of land.

[[Dam]]s and [[reservoir]]s can have major negative impacts on river [[ecosystems]] such as preventing some animals traveling upstream, cooling and de-oxygenating of water released downstream, and loss of nutrients due to settling of particulates.<ref>{{Cite web|title=How Dams Damage Rivers|url=https://www.americanrivers.org/threats-solutions/restoring-damaged-rivers/how-dams-damage-rivers/|access-date=2021-11-25|website=American Rivers|language=en-US}}</ref> River sediment builds river deltas and dams prevent them from restoring what is lost from erosion.<ref>{{Cite web|title=As World's Deltas Sink, Rising Seas Are Far from Only Culprit|url=https://e360.yale.edu/features/as-worlds-deltas-sink-rising-seas-are-far-from-only-culprit|access-date=2021-11-25|website=Yale E360|language=en-US}}</ref><ref>{{Cite web|title=Why the World's Rivers Are Losing Sediment and Why It Matters|url=https://e360.yale.edu/features/why-the-worlds-rivers-are-losing-sediment-and-why-it-matters|access-date=2021-11-25|website=Yale E360|language=en-US}}</ref> Furthermore, studies found that the construction of dams and reservoirs can result in habitat loss for some aquatic species.{{sfn|Breeze|2018|p={{pn|date=March 2025}}}}[[File:Garwnant Hydropower Scheme, Breckon Beacons, Cymru, (Wales).webm|thumb|A hydropower scheme which harnesses the power of the water which pours down from the Brecon Beacons mountains, [[Wales]]; 2017]]Large and deep dam and reservoir plants cover large areas of land which causes [[greenhouse gas emissions]] from underwater rotting vegetation. Furthermore, although at lower levels than other [[renewable energy]] sources,{{Cn|date=March 2024}} it was found that hydropower produces [[methane]] (CH<sub>4</sub>) equivalent to almost a billion tonnes of CO<sub>2</sub> greenhouse gas a year.<ref>{{Cite web |title=Hydroelectricity is a hidden source of methane emissions. These people want to solve that |url=https://www.bbc.com/future/article/20240326-how-hydroelectric-dams-are-a-hidden-source-of-carbon-emissions |access-date=2024-03-30 |website=www.bbc.com|date=27 March 2024 }}</ref> This occurs when organic matters accumulate at the bottom of the reservoir because of the [[deoxygenation]] of water which triggers [[anaerobic digestion]].{{sfn|Breeze|2019|p=116}}

People who live near a [[hydro plant]] site are displaced during construction or when [[reservoir]] banks become unstable.{{sfn|Breeze|2018|p={{pn|date=March 2025}}}} Another potential disadvantage is cultural or [[List of religious sites|religious sites]] may block construction.{{sfn|Breeze|2018|p={{pn|date=March 2025}}}}{{Refn|group="note"|See the [[World Commission on Dams]] (WCD) for international standards on the development of large dams.}}