51 reservoirs with a combined capacity of 11,056 hm³ · latest official reading: 6 October 2026
The Tagus basin is currently at 54.2 % of capacity, above normal for the time of year. The week-41 average across 38 years of records is 46.2 %, a difference of +8.0 points.
For context: a year ago it stood at 61.6 % and a month ago at 57.6 %. Against last week’s reading it is falling (−0.7 points).
Blue line: average monthly filling for the whole demarcation since 1988. The dot marks today’s reading, 54.2 % in October.
With 2,023 weeks of record since 1988, the average pattern of the Tagus basin is clear: it peaks in May at 64.0 % and bottoms out in October at 46.0 %. That 18-point range makes it a markedly seasonal demarcation, with a demanding irrigation season.
The highest reading in the whole series is 85.9 %, on 27 May 2025, and the lowest 30.7 %, on 31 October 1995. Comparing today against those two extremes says more than the bare percentage: 50 % is comfortable in a demarcation that rarely tops 60 %, and worrying in one that usually reaches summer full.
By capacity it is the 1th demarcation of the 14 covered by the hydrological bulletin: its 11,056 hm³ account for 19.7 % of everything Spain can store in mainland reservoirs. Today it holds 5,988 hm³.
The 51 dams the hydrological bulletin tracks in the Tagus basin, sorted by capacity. Linked names have their own page with the full record.
| Reservoir | Capacity (hm³) | Volume (hm³) | Fill | Δ week | Use |
|---|---|---|---|---|---|
| Alcántara II | 3,160 | 1,764 | 55.8 % | −2.1 | Hydropower |
| Buendía | 1,705 | 797 | 46.7 % | +0.4 | Irrigation / supply |
| Valdecañas | 1,446 | 790 | 54.6 % | +1.9 | Hydropower |
| Gabriel y Galán | 911 | 340 | 37.3 % | −0.9 | Irrigation / supply |
| Entrepeñas | 813 | 487 | 59.9 % | +0.0 | Irrigation / supply |
| Atazar, El | 426 | 286 | 67.1 % | −0.7 | Irrigation / supply |
| Cedillo | 260 | 253 | 97.3 % | +0.4 | Hydropower |
| Burguillo - Puente Nuevo | 201 | 89 | 44.3 % | +0.0 | Irrigation / supply |
| Torrejón (Tajo - Tietar) | 188 | 153 | 81.4 % | −10.6 | Hydropower |
| Alcorlo | 180 | 96 | 53.3 % | −0.6 | Irrigation / supply |
| San Juan | 138 | 71 | 51.4 % | −1.4 | Irrigation / supply |
| Finisterre | 133 | 24 | 18.0 % | +0.0 | Irrigation / supply |
| Valmayor | 124 | 84 | 67.7 % | +0.0 | Irrigation / supply |
| Azután | 113 | 79 | 69.9 % | −3.5 | Hydropower |
| Santillana | 91 | 52 | 57.1 % | −1.1 | Irrigation / supply |
| Borbollon | 88 | 38 | 43.2 % | +0.0 | Irrigation / supply |
| Rosarito | 82 | 11 | 13.4 % | +3.7 | Irrigation / supply |
| Tajera, La | 64 | 33 | 51.6 % | −1.6 | Irrigation / supply |
| Jerte - Plasencia | 59 | 29 | 49.2 % | −1.7 | Irrigation / supply |
| Vado, El | 56 | 16 | 28.6 % | −1.8 | Irrigation / supply |
| Beleña | 53 | 21 | 39.6 % | −3.8 | Irrigation / supply |
| Puentes Viejas | 53 | 32 | 60.4 % | +0.0 | Irrigation / supply |
| Valdeobispo | 53 | 50 | 94.3 % | +0.0 | Irrigation / supply |
| Riosequillo | 50 | 32 | 64.0 % | −2.0 | Irrigation / supply |
| Rivera de Gata | 49 | 8 | 16.3 % | +0.0 | Irrigation / supply |
| Castrejón | 44 | 43 | 97.7 % | +0.0 | Hydropower |
| Pardo, El | 43 | 13 | 30.2 % | +0.0 | Irrigation / supply |
| Baños | 41 | 25 | 61.0 % | +0.0 | Irrigation / supply |
| Vellón,El-(Pedrezuela) | 41 | 33 | 80.5 % | +0.0 | Irrigation / supply |
| Pinilla | 38 | 17 | 44.7 % | +0.0 | Irrigation / supply |
| Atance, El | 35 | 18 | 51.4 % | +0.0 | Irrigation / supply |
| Navalcán | 34 | 20 | 58.8 % | −8.8 | Irrigation / supply |
| Bolarque | 31 | 27 | 87.1 % | +0.0 | Hydropower |
| Pálmaces | 31 | 19 | 61.3 % | +0.0 | Irrigation / supply |
| Aceña | 24 | 14 | 58.3 % | +0.0 | Irrigation / supply |
| Portaje | 23 | 16 | 69.6 % | +4.3 | Irrigation / supply |
| Villar, El | 23 | 15 | 65.2 % | +0.0 | Irrigation / supply |
| Cáceres - Guadiloba | 20 | 10 | 50.0 % | +0.0 | Irrigation / supply |
| Guajaraz | 18 | 15 | 83.3 % | +0.0 | Irrigation / supply |
| Picadas | 15 | 11 | 73.3 % | −20.0 | Irrigation / supply |
| Navamuño | 14 | 6 | 42.9 % | +0.0 | Irrigation / supply |
| Salor | 14 | 7 | 50.0 % | +0.0 | Irrigation / supply |
| Guijo de Granadilla | 13 | 12 | 92.3 % | +0.0 | Hydropower |
| Navacerrada | 11 | 4 | 36.4 % | +0.0 | Irrigation / supply |
| Castro, El | 8 | 3 | 37.5 % | +0.0 | Irrigation / supply |
| Almoguera | 7 | 6 | 85.7 % | +0.0 | Hydropower |
| Cazalegas | 7 | 6 | 85.7 % | +0.0 | Irrigation / supply |
| Jarosa, La | 7 | 3 | 42.9 % | +0.0 | Irrigation / supply |
| Torcón | 7 | 3 | 42.9 % | +0.0 | Irrigation / supply |
| Molino de Chincha | 6 | 5 | 83.3 % | +0.0 | Hydropower |
| Portiña, La | 5 | 2 | 40.0 % | +0.0 | Irrigation / supply |
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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.
National summary and reservoir search on Reservoirs of Spain.
