Guadiana Menor river · Guadalquivir Basin · dam built in 1984 · latest official reading: 6 October 2026.
Negratín is currently at 58.5 % of capacity, above normal for the time of year. The week-41 average across 38 years of records is 41.4 %, a difference of +17.1 points.
For context: a year ago it stood at 25.2 % and a month ago at 59.9 %. Against last week’s reading it is falling (−0.2 points).
Blue line: average monthly filling across the whole record, from 1988. The dot marks today’s reading, 58.5 % in October.
With 2,023 weekly readings since 1988, the average pattern of Negratín is clear: it peaks in April at 51.9 % and bottoms out in October at 41.1 %. That 11-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 108.0 %, on 1 March 1988, and the lowest 2.9 %, on 29 August 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 571 hm³ of capacity it is the third largest of the 47 dams the bulletin tracks in the Guadalquivir basin, holding 7.1 % of the whole demarcation’s capacity on its own. The basin as a whole is at 69.1 % 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 47 dams the bulletin tracks: Guadalquivir Basin.
