Irati river · Ebro Basin · dam built in 2004 · latest official reading: 6 October 2026.
Itoiz is currently at 32.9 % of capacity, about normal for the time of year. The week-41 average across 20 years of records is 36.8 %, a difference of −3.9 points.
For context: a year ago it stood at 44.8 % and a month ago at 39.6 %. Against last week’s reading it is falling (−1.2 points).
Blue line: average monthly filling across the whole record, from 2006. The dot marks today’s reading, 32.9 % in October.
With 1,045 weekly readings since 2006, the average pattern of Itoiz is clear: it peaks in May at 80.0 % and bottoms out in October at 37.3 %. That 43-point range makes it a reservoir with a marked annual swing, typical of heavy irrigation use.
The highest reading in the whole series is 100.7 %, on 29 April 2008, and the lowest 16.3 %, on 14 October 2008. 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 417 hm³ of capacity it is the sixth largest of the 76 dams the bulletin tracks in the Ebro basin, holding 5.3 % of the whole demarcation’s capacity on its own. The basin as a whole is at 45.4 % 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 2006. 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 76 dams the bulletin tracks: Ebro Basin.
