Olt river · Copernicus elevation · Landsat

The river of stairs

Along its 619 km mapped course the Olt falls 878 m, from 896 m to 18 m. Now 27 dams split it into a chain of lakes. Scroll to go down the river.

White water first

In its first 250 km the Olt drops about 458 m. No dam of the cascade stands here, so the line shows the river surface as the Copernicus model saw it.

Through the Carpathians

From Avrig to Turnu the river crosses the Southern Carpathians, partly through the Olt gorge, and falls 106 m in 71 km. The newest steps are here: Cornetu in 2001–02, Robești in 2012, Racovița in 2019. Two more plants, Lotrioara and Câineni, were still unfinished in 2026.

Back to 1970

Every step in the profile is a lake. The clock now goes back to 1970, then forward. Each lake rises in the year its plant went into service (INHGA's plant tables; Hidroelectrica for the three newest).

13 dams in nine years

From 1974 to 1982 13 dams rose between Turnu and Slatina. Below Cozia the river became a chain of lakes, with steps of 10 to 24 m between them. Landsat's record starts in 1972, so for some of these lakes it can still watch the water arrive.

A second wave, 1986 to 1996

The lower Olt got five more steps, from Ipotești in 1986 to Izbiceni in 1996, while the upper river was dammed at Voila, Viștea, Arpașu, Scoreiu and Avrig.

The last steps

Cornetu followed in 2001–02, Robești in 2012 and Racovița in 2019. Between Voila and Izbiceni the documented heights of fall add up to 369 m, out of a fall of 394 m; the model's steps add up to 308 m.

27 steps

Scroll on to find the lake nearest you, and to see which numbers we could check and which we could not.

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Your lake

Which lake is nearest you?

Type the name of a town or commune within 25 km of the river. You get the lake, the year its plant went into service, the height of fall and the area of the water in Landsat's 2025 images.

Town or commune

What we checked

Can a satellite elevation model see the steps?

Mostly, and it reads low. For 26 of the 27 dams we measured the drop in the Copernicus elevation model from the lake surface to the river below it, and set it against the height of fall printed in INHGA's plant table. The median difference is 1.5 m, 16 of 26 agree within 2 m, and 16 read more than 1 m lower. Racovița is left out: the model dates from about 2011–15 and the dam from 2019, so the step is not in it. The dashed line is a perfect match. The documented heights add up to 369 m, the model's steps to 308 m.

Where each number comes from

Years and heights, dam by dam

27 dams on the Olt between Voila and Izbiceni. Year and height of fall come from the plant tables of INHGA, the national hydrology institute; dam height and volume from the 2023 list of A.B.A. Olt, the river basin authority. Where Global Dam Watch gives another year, it is shown in its own column. 13 of the 17 dams that Global Dam Watch lists carry the same year, 17 within one year.

Dam	km from start	Year	GDW year	Landsat fill year	Head m (INHGA)	Step m (DEM)	Dam m (A.B.A.)	Water km²
Voila	301	1989	1988	1989	10	7	21	1.6
Viștea	310	1989	1989	1990	10	4.5	21	1.8
Arpașu	324	1991	1990	1991	10	8.5	22	2.6
Scoreiu	332	1992	1992	1993	10	5	22	2.0
Avrig	343	1996	1996	1997	10	10	22.5	3.1
Racovița	354	2019	–	2015	13.5	2	21.5	3.4
Robești	385	2012	–	–	12	7.5	21.5	1.6
Cornetu	394	2002	–	–	12	10.5	22.5	1.4
Gura Lotrului	403	1986	–	1984	12	9.5	25	1.3
Turnu	414	1982	–	–	24	22.5	44	1.2
Călimănești	418	1981	1981	–	14.5	13	28.5	0.8
Dăești	427	1976	1976	–	13.5	11	27.6	2.1
Râmnicu Vâlcea	435	1974	1974	–	16.5	14.5	35.6	3.4
Râureni	442	1977	–	–	18	14.5	29	2.6
Govora	451	1975	1975	–	15.5	12	26	3.7
Băbeni	463	1978	1978	1979	14	14	32.8	8.1
Ionești	469	1978	1978	1979	14	13	35.4	4.2
Zăvideni	479	1979	1979	1981	14	14	30.5	10.7
Drăgășani	490	1980	1980	1981	16	16	31.5	12.5
Strejești	507	1979	1978	1979	18	16.5	33	23.7
Arcești	517	1980	1980	1981	14	14	30.5	9.3
Slatina	525	1981	1980	1980	10	9.5	24	6.4
Ipotești	540	1986	1986	1987	13.5	13	31.5	15.9
Drăgănești-Olt	553	1987	–	1988	13.5	14	29.5	12.1
Frunzaru	570	1988	–	1992	13.5	13.5	29.5	15.5
Rusănești	585	1989	–	1991	13.5	8	29.5	12.5
Izbiceni	599	1996	–	1997	13.5	10	31.5	10.1

Check 1 · dams: partly met

We set the test before building: every dam needs a year and a height of fall from one source. No single source gave both for every dam. A.B.A. Olt's 2023 list names the dams and gives dam height and volume, but no year. INHGA's plant tables give both year and height of fall, for 25 of the 27 dams; for the other 2 (Racovița, Robești) INHGA's table lists a plant 'under construction', and we took the year from Hidroelectrica's 2026 environmental report. We did not open the INHGA table ourselves: its numbers come from a transcription of a copy, so the heights of fall are checked only by the elevation model above. The years were set against a second source (Hidroelectrica and county plans); they differ by more than a year for four dams (noted on the lake card), and for one, Gura Lotrului, the second source could not be opened.

Check 2 · drowned villages: not met

We needed at least five drowned villages, each named in a map or history from before the flooding and tied to a lake by a second document. We found none. We ran two independent searches (local histories, village pages, press) and read the Wikipedia pages of more than 30 riverside communes, and found only these traces: Robești was kept in place when the plant was built; Râul Vadului and Priloagele were named in 1978 for relocation because a larger reservoir would flood them, and it was never built; at Mândra land was flooded, and the documents we found do not show houses lost. A name on an old map is not proof that the village is under the lake, so this page names no drowned village.

Where to look next: the county archives in Vâlcea and Olt (the Arhivele Naționale), the Austrian third military survey sheets (1869–87, on Arcanum), and the monographs of the communes on the shore.

How it was measured

The method in short

The profile is the Copernicus GLO-30 elevation model (surface about 2011–2015) sampled every 100 m along OpenStreetMap's Olt line, taking the lowest value within 120 m either side. The line is 619 km long; its start is at 896 m. Because the model dates from after most dams, the lakes are already in it: the flat steps are real, except at Racovița.
The river line before each dam is not measured: it is drawn as a straight line from the end of the lake to the foot of the dam. The water under the lake surface is shaded down to that line, so its bottom is a drawn estimate, not a measurement. The page draws the line dashed and says on screen that it is drawn.
The strip and the lake maps come from Landsat 1–9 (Planetary Computer): multispectral scanner images for 1972–83, thematic mapper and later for 1984–2025, June to October, up to six clear looks a year. A pixel counts as water when a water index (NDWI for the early scanner, MNDWI after) is above zero. The map shows the year each pixel became water and stayed water, with one dry year tolerated.
For the 13 dams put into service before 1984 the satellite record is short: Landsat 1–3 images begin in 1972 and clear summer looks exist from 1975. Where a lake is already full in its first clear look, the page says so and does not show a filling.
Landsat's fill year differs from the documented year by a median of 1.0 years across the 19 lakes where the satellite saw the filling. The year a plant went into service and the year the satellite sees the lake full are different events.

Sources

INHGA, Bazinul hidrografic Olt, plant tables (year, height of fall, MW).
A.B.A. Olt, Planul de management al riscului la inundații, ciclul II (October 2023), Annex 4a: dam height and volume.
Global Dam Watch v1.0 (GDW), reservoir areas and a second year for 17 dams.
Hidroelectrica, environmental report for the Cornetu–Avrig development (March 2026): years for Cornetu, Robești, Racovița.
Copernicus GLO-30 DEM (ESA/Copernicus). OpenStreetMap contributors (ODbL), river line. Landsat Collection 2 (USGS/NASA) via Microsoft Planetary Computer. UAT outlines 2025.