Guadiela river · Tagus Basin · dam built in 1958 · latest official reading: 6 October 2026.
Buendía is currently at 46.7 % of capacity, far above normal for the time of year. The week-41 average across 38 years of records is 20.6 %, a difference of +26.1 points.
For context: a year ago it stood at 47.2 % and a month ago at 47.3 %. Against last week’s reading it is rising (+0.4 points).
Blue line: average monthly filling across the whole record, from 1988. The dot marks today’s reading, 46.7 % in October.
With 2,023 weekly readings since 1988, the average pattern of Buendía is clear: it peaks in June at 28.9 % and bottoms out in October at 20.5 %. That 8-point range makes it a very stable reservoir through the year, as hydropower pools and very large dams tend to be.
The highest reading in the whole series is 59.6 %, on 14 April 2026, and the lowest 4.1 %, on 14 November 1995. Comparing today against those two extremes says more than the bare percentage: 50 % is good news in a pool that rarely tops 60 %, and bad news in one that is usually full.
At 1,705 hm³ of capacity it is the second largest of the 51 dams the bulletin tracks in the Tagus basin, holding 15.4 % of the whole demarcation’s capacity on its own. The basin as a whole is at 54.2 % today, so this reservoir is running below the basin as a whole.
The figures on this page come from the official MITECO reservoir archive, the same database behind Spain’s weekly hydrological bulletin. The bulletin covers every mainland reservoir above 5 hm³ of capacity and is published every Tuesday with Monday’s reading.
The latest reading here is from 6 October 2026, and the comparison series starts in 1988. Nothing is estimated, interpolated or forecast: the percentage is stored volume divided by the usable capacity the bulletin itself assigns to the dam. Historical averages are computed over the same calendar week in every previous year, the only fair comparison in a system with such marked seasonality.
See the whole demarcation, with all 51 dams the bulletin tracks: Tagus Basin.
