Dam-Affected and Regulated Waterfalls: Then and Now
Half of Europe's named major waterfalls and many in Africa, Asia and the Americas no longer flow as they did before hydropower. Some have schedules; others run only after wet seasons. This guide surveys the major affected falls — and the few that successfully resisted.
The classic case: Marmore
Italy's Cascata delle Marmore (165 m, Roman-engineered) runs on ENEL's tourist schedule: 11-13 and 16-17 in summer; outside these hours the water powers a hydroelectric plant. The schedule prioritises tourism without sacrificing power generation.
Cascate del Serio: five days a year
The tallest free-falling waterfall in Italy (315 m) is dry except for five scheduled summer-and-autumn releases from the Barbellino dam. Outside these days the riverbed is empty.
Mardalsfossen, Norway
Norway's 705-metre cascade is regulated — the river is dammed and most flow goes to power generation. By Norwegian agreement, full flow is restored June 20 to August 20 only.
Niagara: the 1950 Treaty
The Niagara River Treaty (1950) requires 100,000 cubic feet per second (cfs, ~3,000 m³/s) over the falls minimum during summer daylight, 50,000 cfs at night and in winter. The rest goes to US-Canadian power plants.
Blue Nile Falls (Tis Abay)
Ethiopia's iconic falls have been severely reduced since 2003 by the Tana-Beles hydroelectric scheme upstream. Outside of monsoon floods, the fall is a thread of its former self.
Sigríður and Gullfoss
Iceland's Gullfoss was nearly dammed in the early 1900s by British speculators. Sigríður Tómasdóttir's protest (walking barefoot to Reykjavík) saved the falls; today they run unregulated.
Iguazú and Itaipu
Iguazú flows naturally — but the Itaipu Dam, 20 km downstream on the Paraná, is the world's largest hydroelectric facility (14 GW). The 1973 treaty between Brazil, Paraguay and Argentina protected the Iguazú itself from being dammed.
The trade-off
Hydropower is renewable and emissions-free; ungimped waterfalls are irreplaceable. Most modern projects build run-of-river systems that preserve at least minimum scenic flow. Visitors should check seasonal release schedules.
From reading to planning
All of these are pinned on our interactive map.