Víboras river · Guadalquivir Basin · dam built in 1995 · latest official reading: 6 October 2026.
Víboras is currently at 47.1 % of capacity, above normal for the time of year. The week-41 average across 21 years of records is 38.5 %, a difference of +8.6 points.
For context: a year ago it stood at 29.4 % and a month ago at 47.1 %. Against last week’s reading it is essentially flat (+0.0 points).
Blue line: average monthly filling across the whole record, from 2005. The dot marks today’s reading, 47.1 % in October.
With 1,112 weekly readings since 2005, the average pattern of Víboras is clear: it peaks in June at 51.6 % and bottoms out in October at 39.1 %. That 12-point range makes it a reservoir with a moderate annual swing.
The highest reading in the whole series is 63.2 %, on 23 March 2010, and the lowest 5.3 %, on 11 October 2005. 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 17 hm³ of capacity it is the 44th largest of the 47 dams the bulletin tracks in the Guadalquivir basin, holding 0.2 % 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 2005. 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.
