Water level at major reservoir feeding Malaga drops to all-time low

The Guadalhorce reservoir in Malaga province has dropped to a record low level, recording just 11.9 cubic hectometres of water as of Tuesday 24 September.

The figure is worse than the previous all-time low, recorded 15 years ago. Official records started in 1997, however according to SUR archives, no worse data had been recorded in the 1995 or 1982 droughts either. Although in those years, the supply was much weaker, with no desalination plant to treat the salinated water of the Guadalhorce itself and the wells, and with fewer reservoirs in the province. The Marbella desalination plant, now being upgraded, was also not in operation.

At mid-morning, the Guadalhorce reservoir had barely 11.75 cubic hectometres in storage. Together with the Guadalteba and Conde, the three main sources of supply to Malaga, they totalled just 48 cubic hectometres. This is enough water for ten months, bearing in mind the city consumes 54 cubic hectometres annually, of which a significant amount is brine.

The Guadalhorce and Guadalteba reservoirs, which are connected, were built between 1966 and 1973. In the case of the Guadalhorce reservoir, it is also heavily salinated, as several hypersaline springs, the main one being Meliones, flow into the reservoir's tail area. The concentration level can be seven times higher than that of seawater, with drought worsening these concentrations.

A plan to isolate these catchments in the reservoir itself has never worked. Pumping, diversion pipes and other solutions have been tried, but to no avail. What has worked is mixing the water from the three reservoirs to lower its salt level before it is treated, and then finally refined in the desalination plant at El Atabal.

Before the desalination plant, Emasa had to do real alchemy to put decent drinking water into the network, which still had high levels of lime and salt. This has changed radically since 2005. The salt in the Guadalhorce now exceeds 4,000 microsiemens (2.56 grams per litre), measured at the Paredones weir, where the irrigation canals are separated from the water that runs to Malaga city.

In 2022, with considerably more water in the reservoirs, the figure was about 2,000 microsiemens of salt. That 2,000 is about one gram per litre, which is what the irrigation can handle. In any case, the desalination plant could treat up to 10,000 microsiemens. But the more effort, logically, the higher the energy costs and the shorter the useful life of the equipment.

As it is, the reservoir is at 9% of its capacity. The Guadalteba, the second largest in Malaga province after La Viñuela, has around 20 cubic hectometres and is at 13%, and the Conde del Guadalhorce has around 16 cubic hectometres and is at 23%. The Conde del Guadalhorce was completely empty during the drought of 1995 and had almost reached rock bottom again in November of last year, but rains in March this year allowed it to recover some water.

There is water for less than a year in Malaga city; there is water for a year but only for urban uses in the Axarquía, and the Costa del Sol is a little better off but, given the size of the La Concepción reservoir in Marbella and despite the upgrade of the desalination plant, there is no room for confidence. It is to be expected that the drought committee will impose new restrictions in a few days.

All the reservoirs in the province store 105 cubic hectometres and are at 17% capacity. In the case of Malaga city, the reservoirs of El Limonero and Casasola could also supply some water, but they are reserves that are hardly used and only contain four cubic hectometres and five cubic hectometres, respectively.