In the middle of the twentieth century dam building boomed, and the rising water took villages, towns and whole valleys with it. This map brings together the 100 places that English Wikipedia records as flooded by a reservoir, from Capel Celyn in Wales to Mologa on the Volga, and sets them against 82,360 dams in Wikidata.
In 1965 the valley of the Tryweryn, north west of Bala, was flooded to make a reservoir for Liverpool. Capel Celyn, one of the last Welsh-only speaking communities in the area, went under the water of Llyn Celyn, and 48 of the 67 people who lived in the valley lost their homes. The scheme was opposed by 125 local authorities and won no support from Wales' 36 members of Parliament, but Parliament passed it anyway. Liverpool City Council apologised in 2005. Graffiti near Llanrhystud reading Cofiwch Dryweryn, "remember Tryweryn", became an icon of Welsh feeling.
Capel Celyn was one village among many. Through the twentieth century engineers built dams faster than ever before, for drinking water, irrigation, flood control and electricity, and each new reservoir filled a valley that people lived in. This page maps the drowned places that have an English Wikipedia article, reads from each article what drowned it and when, and sets them against the dams that Wikidata records. It also maps the towns that the sea took, because Wikipedia files them in the same categories, but it leads with the reservoirs.
Symbols: places with an English Wikipedia article in the categories Submerged places, Communities depopulated for reservoir creation, Populated places inundated by the Tennessee Valley Authority, The Lost Villages, Underwater ruins and Flooded valleys, classed from the article's opening text: dark blue, flooded by a reservoir; teal, sunk by the sea, a lake or a river; grey, submerged but the text read does not say how. Rings: large reservoirs from Wikipedia's articles, with the number of people displaced as the article states it. Dots: 82,360 dams in Wikidata, sized by recorded height where usable and coloured by the decade of inception where known (grey: no date). "By year" shows dams by their inception year and places by the year or decade their article gives. Sources: English Wikipedia (CC BY-SA 4.0); Wikidata (CC0); outlines Natural Earth. Optional base map tiles © Esri.
Wikidata lists 82,360 dams with coordinates, but it gives a building date for only 3,128 of them (3.8%). The list is lopsided: 69% of the dams are in the United States, and only 295 of those have a date, while Japan has dates for 1,192 of its 2,180, more than a third of all the dated dams. So the chart below is not a census of the world's dams. But its shape is clear. From fewer than 25 a decade before 1900, dated dams rise to 170 in the 1930s, jump to 375 in the 1950s and peak at 538 in the 1960s and 539 in the 1970s, before falling back to 244 in the 1990s. 46% of all the dated dams were built in those three decades, 1950 to 1979.
Dams with a known date, by decade of inception
Wikidata items that are a kind of dam, with an inception year (3,128 of 82,360), stacked by country. Hover or tap a bar.
Reservoirs tell the same story. Wikidata dates 7,381 of its 27,951 reservoirs, 91% of the dated ones in China, and 60% of those dated since 1800 have an inception between 1950 and 1979, with a peak of 1,636 in the 1970s. Within the boom years, the dated dams come mostly from Japan (51%), Canada (10%), the United States (8%) and India (4%). That ranking says more about which countries' dams are well described in Wikidata than about who built most, but the timing holds across all of them.
Reservoirs with a known date, by decade
Wikidata reservoirs with an inception year since 1800 (7,297), China and everywhere else.
Of the 68 drowned places whose article dates the flood, 60 went under between 1930 and 1979.
I found 186 pages in the six Wikipedia categories and their subcategories. 40 are not submerged places at all (kings, languages, temples, bridges, lists and the like) and are set aside. Of the 146 that remain, 100 were flooded by a reservoir, 28 were sunk by the sea, a lake or a river, and for 18 the opening text does not say how. The reservoir places are spread over 13 countries, but 64 of them, 64%, are in the United States, which has the most articles of this kind by far; that is partly a measure of Wikipedia's coverage, not only of where the water rose.
Drowned places by country
Places with an article, by what drowned them. Countries with at least two places; the rest grouped.
Where the article gives a date, the flooding follows the dams. The earliest is Llanwddyn in Wales, drowned by Lake Vyrnwy in the 1880s; the latest, Zeugma on the Euphrates, flooded by the Birecik Dam in 2000. The busiest decade is the 1950s, with 22 places. Some reservoirs drowned several: the St Lawrence Seaway took ten communities in 1958, Tellico Lake four sites in Tennessee, and Camanche Reservoir and Riffe Lake three each.
When the reservoirs came
Drowned places by the decade their article gives for the flooding, the filling or the dam's completion (68 of 100).
Britain's best known drowned villages lie in Wales and the north, and most were flooded to supply cities somewhere else. Liverpool came first. Lake Vyrnwy was built in the 1880s for Liverpool Corporation, and drowned the original village of Llanwddyn; the article lists a church, two chapels, three inns, ten farmhouses and 37 houses demolished, and the water still travels 109 km by aqueduct. Birmingham followed: an Act of 1892 gave Birmingham Corporation the power to move more than 100 people out of the Elan Valley, where the reservoirs first filled in 1896. Then Manchester raised Haweswater in the Lake District, and the hamlet of Mardale Green went under in the 1930s; its ruins still reappear when the water is low. In the Peak District, Ladybower Reservoir drowned Derwent and Ashopton in the 1940s to supply Nottingham, Derby and Leicester, and Derwent's church tower stood above the water until it was blown up in 1947. Last came Tryweryn.
Drowned valleys and the cities they supply
Straight-line distance from each drowned village or reservoir to the city its article names. Dark blue: drowned places with an article; red: cities.
As the crow flies, Capel Celyn is 74 km from Liverpool, Llanwddyn 81 km, and the Elan Valley 122 km from Birmingham. Mardale Green is 118 km from Manchester. That distance, a valley in one country made to serve a city in another, is why Tryweryn still matters in Wales: the article on the flooding links the failed campaign to a rise in support for Plaid Cymru and, in time, to devolution.
On 1 July 1958, Inundation Day, the water behind the St Lawrence Seaway's new Moses-Saunders power dam began to rise over the Canadian shore near Cornwall, Ontario. Ten communities, nine villages and a populated island, went under: Aultsville, the second largest, had 312 people at the time. Their people were moved to two new planned towns, Long Sault and Ingleside, and some of the buildings were carried away to a museum village. They are remembered as the Lost Villages.
In the United States the Tennessee Valley Authority built dams along the Tennessee River and its tributaries. Wikipedia's category of places it inundated has 15 articles kept here, in Tennessee, North Carolina, Alabama and Kentucky, with dates from 1936 to 1979. Loyston, about 70 people, went under Norris Dam's lake in 1936, after the TVA had surveyed its residents and the photographer Lewis Hine had documented the town. The last, in 1979, were Morganton and the Overhill Cherokee town sites of Chota, Tanasi and Tuskegee, flooded by Tellico Lake; Tanasi gave the state of Tennessee its name. Further west, Elbowoods in North Dakota, the agency seat of the Mandan, Hidatsa and Arikara Nation, was submerged by Lake Sakakawea in 1954.
Many of these American towns were fading long before the water came. For 10 drowned American settlements the article gives both the year the post office closed for good and the year of the flood. The median gap is 35 years: Ellsworth, Indiana lost its post office in 1916 and went under the Patoka Reservoir in 1978, 62 years later. For others the dam came almost at once: Armstead, Montana kept its post office until 1962 and was flooded in 1964.
From the last post office to the flood
Drowned American settlements whose article gives both years. Open circle: post office closed for good; filled: flooded. Hover a row.
On the Volga, the Rybinsk Reservoir began to fill in 1941; the article says some 150,000 people were resettled and the town of Mologa and 663 villages disappeared under the water. Upstream, the Uglich Reservoir took the kremlin and cathedral of Sknyatino in 1939 and the Ivankovo Reservoir the town of Korcheva. The article on Mologa records that 294 people refused to leave and drowned. Further east, Ilimsk on the Angara and the old town of Shagonar on the Yenisei went under new reservoirs in the 1970s. In all, 8 places in Russia and Ukraine here were flooded by reservoirs.
The largest schemes displaced people on another scale. The articles give, for Lake Nasser behind the Aswan High Dam, 100,000 to 120,000 Nubians resettled in Egypt and Sudan, among them 50,000 to 70,000 moved from the old town of Wadi Halfa; the temples of Abu Simbel were moved to save them from the water. For Lake Volta in Ghana, 78,000 people from 740 villages; for Lake Kariba on the Zambezi, about 57,000 Tonga people; for Hasankeyf in Turkey, completely under water by July 2020, up to 80,000. For the Three Gorges Dam on the Yangtze, estimates run from 1.13 million to around 1.4 million.
People displaced by some of the largest reservoirs
The number each Wikipedia article gives (the lower figure where it gives a range). Not a complete list: only the reservoirs whose articles were read for this study.
They are also some of the biggest bodies of water people have made. Lake Volta covers 8,502 square kilometres and is, in its article's words, the largest artificial reservoir in the world by surface area; Lake Kariba covers 5,400, Lake Nasser 5,250 and the Rybinsk Reservoir 4,580. I would have liked to rank every reservoir from Wikidata, but its areas and volumes carry no units in this extract and mix them freely: Ladybower's area is given as 210 (hectares, by its article) and Lake Volta's as 8,502 (square kilometres), so the figures here come from the articles.
The largest reservoirs in the articles read
Surface area in square kilometres, from each Wikipedia article's infobox.
In the Alps the drowning left a landmark. When the dam at Lake Resia was finished in July 1950, the old village of Curon, Graun in German, was flooded; it had been abandoned and largely demolished, and Graun was rebuilt on the new shore. Its church bell tower still stands in the lake. Others reappear in droughts: the old church of Sant Romà de Sau in Catalonia, whose bell tower always shows above the water, Quechula in Mexico, whose old church showed again in the droughts of 2002, 2015 and 2023, and Curdi in Goa, parts of which rise above the water each spring for about a month.
Heights in Wikidata are patchy too: 6,806 dams have one, recorded without a unit. A few are impossible as metres (Oroville in California is given as 770), and the American heights in this extract mix feet and metres, so I leave the United States out and drop anything over 400 m. What remains puts Rogun and Norak in Tajikistan, Grande Dixence in Switzerland and Enguri in Georgia at the top. The Three Gorges Dam is recorded at 181 m, Atatürk at 169 m and Kariba at 128 m.
The tallest dams with a recorded height
Wikidata heights as recorded (outside the United States, up to 400 m). Not checked against other sources.
Wikipedia's categories also hold 28 places lost without any dam. Most went to the sea. On the Yorkshire coast Ravenser Odd was destroyed by the great storm of January 1362, and Ravenspurn is one of more than 30 places on the Holderness coast lost to the North Sea; Dunwich in Suffolk, once the capital of the Kingdom of the East Angles, has mostly gone to coastal erosion, and Hampton-on-Sea in Kent was finally drowned by 1921. Port Royal in Jamaica was destroyed by an earthquake and tsunami in 1692. Off Greece, Pavlopetri is described as the oldest submerged city known, and Helike was swallowed by a tsunami in 373 BC. In Argentina, Villa Epecuén went under the Laguna Epecuén in 1985, when a seiche broke a nearby dam and then the dike protecting the village. Turn the classes on and off above to compare them with the reservoirs.
All 146 places kept, with the reservoir and year their article gives. Click a row to see it on the map.
Drowned places. I took every article in Wikipedia's categories Submerged places (with its subcategories by country), Communities depopulated for reservoir creation, Populated places inundated by the Tennessee Valley Authority, The Lost Villages, Underwater ruins and Flooded valleys: 186 pages, retrieved in 2026. I set aside 40 that are not drowned places, including 4 lists and pages reached only through the Tartessos and Dwarka subcategories. For each of the rest I read the opening of the article (the infobox and the lead, the first 5,000 characters of its wikitext) and recorded the sentence that says how the place went under. If it names a reservoir, a dam, a man-made lake or the St Lawrence Seaway, the place counts as flooded by a reservoir; if it names the sea, a tsunami, an earthquake, erosion, a storm, a natural lake or a river, as sunk by nature. Four pages in the reservoir categories say nothing more and count as reservoir by their category. The rest stay as "cause not stated". The year is the one the article gives for the flooding, the filling or the completion of the dam; where it gives only a decade I keep the decade.
Dams and reservoirs. Wikidata items that are a kind of dam (82,360 with coordinates) and reservoirs (27,951), with inception, height, country and, for dams, the reservoir they created. I use the earliest inception year where there are several. Heights and areas carry no unit in the extract; I use heights only outside the United States and below 400 m, and I do not rank reservoirs by Wikidata's areas. On the map, places without a stated year use the inception year of the reservoir or dam their article names, where Wikidata has one (15 places); none of the counts above use those years.
Distances and lags. Distances are straight lines between the drowned place (or, for the Elan Valley and Ladybower, the reservoir's coordinates in its article) and the city centre in Natural Earth. The lag is the flood year minus the year the article says the post office closed for good; for one place, Hullville in California, the post office outlived the dam, perhaps because it moved.
What this is not. This is a map of drowned places with a Wikipedia article, and many of the largest schemes, Three Gorges, Kariba and Volta among them, drowned hundreds of villages that have no article of their own. Coverage is uneven: American places dominate, and most of the Soviet, Chinese, Indian and African losses appear here only as totals from a handful of articles. The numbers of people displaced are the articles' own, and are estimates. Wikidata's dates cover 3.8% of its dams, mostly in a few countries.