Spain's water reserves drop below 70% for first time in four months: these are the areas storing the least

For the first time in four months, the nation's water reserves have fallen below 70%, the level reached in mid-March. They currently stand at 69.7%, storing 39.073 billion cubic metres after losing 783 million cubic metres in the last week, 1.4 percentage points less than seven days ago, when they stood at 71.1%.

The situation, however, is much more favourable than a year ago, when all Spain's reservoirs were below 62% (7% lower) and held 34.6 billion cubic metres, some 4.4 billions less than now. Compared to the average for the last ten years (58%), we are also much better off today: 11 percentage points higher and 7.5 billion cubic metres more. In fact, this week, the 29th of the year, is the week in which Spain's reservoirs have stored the most water since 2014.

In the last month reservoirs have dropped from 75.6% of their capacity to the current 69.7%, almost six percentage points less. In total, almost 4.1 billion cubic metres have been released in the last 30 days compared to the 2.4 billion during the same period last year. This is 70% more thanks to the fact that, this summer, the drought restrictions in place a year ago in the river basins to the south and east of the country are not in place. However, we have to go back to 2014 (11 years ago) to find the same week in July (week 29) with so much water in the reservoirs.

Data provided by Spain's ministry for ecological transition also indicates that last weekend's torrential rains, with levels in excess of 100 litres per square metre in municipalities in several regions such as Aragon, Catalonia and Valencia, have not been felt in their reservoirs. In general terms, their reservoirs have, in fact, lost water.

The Basque Country's inland river basins top the list of basins with the fullest reservoirs. They are at 90.5% capacity. Above 80% are the Tinto, Odiel and Piedras (85%), the Duero (81.6%) and the Miño-Sil (81.1%).

The remaining basins, except for the Segura and the Guadalete-Bárbate are above 50%. The list is as follows: Ebro (79.8%), Eastern Cantabrian (79.4%), Western Cantabrian (79%), Catalonia's inland basins (78.1%), the Tagus (77%), the Guadiana (65.5%), Galician coast (62%), the Júcar (59%), the Andalusian Mediterranean basin (53.9%) and the Guadalquivir (53.7%). Finally, the Guadalete-Barbate is at 49.8%, followed by the Segura at 29.6%.

By Spanish region, according to data collected on the embalses.net website, all are above 50%, except for the regions of Valencia at 49.5% and Murcia at 34.4%. However, in both cases their water reserves are well above what they were at this time last year. In 2024 they were at 39% and 23% respectively (between ten and eleven points lower than now).

We cannot leave behind the data by region without looking at the situation with Andalucía for the remainder of the summer. It's worth mentioning that its reservoirs are at 54% (16 points more than in the same week in 2024). However, there are notable differences between the region's provinces: from 80% accumulated by the reservoirs in Seville to less than 10% in those of Almeria (9.8%). Or from 74% in the reservoirs of Huelva to 38% in those of Granada.

The reservoirs of Catalonia are also in an optimal situation, a region that has gone from suffering restrictions due to drought (last summer swimming pools could not be filled and garden irrigation was banned) to an abundance of water in just one year. They are currently at 83% of their capacity, 20 points more than a year ago.

By province, all of Spain's reservoirs are on average above 50%, except for the aforementioned reservoirs of Almeria, Granada and Murcia, to which are added those of Alicante (24.7%), Albacete (29.8%) and Jaen (45%), all of them concentrated in six provinces in the southeast of the country, traditionally the area hardest hit by drought.

For Jorge Olcina, professor of regional geographic analysis at the University of Alicante and expert in climatology, "being at almost 70% is a very good figure, something that has not been recorded for many years", and it will ensure urban and agricultural water supplies "this summer for sure, and until the end of the year, I'd say too, because then we have to wait for the autumn rains."

Prof Olcina says there might be some specific exceptions in small, inland, mountain towns "with poorly designed supply systems or low-capacity water tanks" that may run out of supplies in the summer. "They may have very specific supply problems but, in general, the supply is guaranteed."

To ensure consumers are aware of the importance of controlling their water consumption, the climatologist points out that, between how often we turn on that tap and water evaporation from the reservoirs due to the heat, we lose between 500 and 800 million cubic metres of water per week. "Almost half of what we gained in nine months, from last September to May, we've lost in the last three months. I say this so that we're aware that we need to spend water very prudently. We have a guaranteed supply, but we shouldn't waste water, far from it."