Júcar river · Júcar Basin · dam built in 1955 · latest official reading: 6 October 2026.
Alarcón is currently at 71.4 % of capacity, far above normal for the time of year. The week-41 average across 38 years of records is 32.9 %, a difference of +38.5 points.
For context: a year ago it stood at 59.8 % and a month ago at 72.1 %. Against last week’s reading it is essentially flat (+0.1 points).
Blue line: average monthly filling across the whole record, from 1988. The dot marks today’s reading, 71.4 % in October.
With 2,023 weekly readings since 1988, the average pattern of Alarcón is clear: it peaks in April at 42.9 % and bottoms out in October at 32.6 %. That 10-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 81.3 %, on 22 April 2014, and the lowest 2.5 %, on 2 August 1994. 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 1,118 hm³ of capacity it is the largest of the 23 dams the bulletin tracks in the Júcar basin, holding 39.3 % of the whole demarcation’s capacity on its own. The basin as a whole is at 51.9 % today, so this reservoir is running above 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 23 dams the bulletin tracks: Júcar Basin.
