Portel, Portugal, Feb. 5, 2026 (Lusa) - The Alqueva reservoir, Europe's largest artificial lake, increased its water discharge to 3,300 cubic metres per second (m3/s) on Thursday due to "persistent high tributary flows" caused by heavy rains, the managing company said.
In comparison, an Olympic swimming pool only has 2,500 m3. so it would tak well under a second to fill a poll like this with that discharge rate.
A source from the Alqueva Development and Infrastructure Company (EDIA) explained to the Lusa news agency that this morning, the "discharge flow" from the dam, whose wall is located between the municipalities of Portel, in the district of Évora, and Moura, in the district of Beja, on the Guadiana River, was increased.
"We increased the discharge because the inflows to Alqueva remain high," the source said.
The 3,300 m3/s, he said, is achieved thanks to "the 2,500 m3/s of flow being discharged [through the two half-depth spillways that are open] and the four groups of the two hydroelectric power stations that are turbining 800 m3/s".
The flow reaching the Pedrógão Dam, located about 23 kilometres away in the neighbouring municipality of Vidigueira, in the district of Beja, comes from Alqueva and from the tributaries of the Ardila River, "which has a very high flow".
"Pedrógão has a discharge flow of around 4,000 m3/s" into the Guadiana River, which means it is "discharging the maximum since the Alqueva floodgates were closed," said the source from the company that manages this multipurpose project (EFMA).
Due to bad weather and the high volume of water stored, discharges into the river began at the Pedrógão Dam on the morning of 28 January.
On the same day, at 4 pm, the Alqueva Dam opened its mid-depth spillways and began controlled discharges, as the reservoir was close to its full storage level.
At the time, the initial discharge flow was 600 m3/s, which, when combined with the turbine flow, resulted in a total discharge of 1,200 m3/s, EDIA reported, adding that from Pedrógão the discharge was 1,500 m3/s.
After 48 hours, the operation was suspended and resumed on Monday due to the "persistence of high inflows".
Alqueva then began to release a total flow of 1,400 m3/s, and on Wednesday, the volume of water discharged rose again to 2,050 m3/s (in Pedrógão 2,700 m3/s, including inflows from the Ardila River), according to a source at EDIA today, who emphasised that, as of Thursday, the new total is 3,300 m3/s (4,000 m3/s from Pedrógão).
During the operations of the last few days, the company recommended that, given the risk of flooding, the population should adopt "precautionary behaviour in potentially affected areas" and called for "the cooperation of all entities and riverside populations in preventing risky situations".
The last controlled discharge operation in Alqueva was carried out in 2013 to manage the reservoir's water volume, which was approaching its maximum storage capacity (this had happened twice before).
The maximum level of the Alqueva reservoir is 152, which corresponds to a total storage capacity of 4,150 cubic hectometres of water.
RRL/ADB // ADB.
Lusa
