The ghost dam of Montejaque: New docuseries reveals secrets of Europe’s greatest engineering failure
Filmmaker José Luis Matoso spent 15 years investigating the 'dam with feet of clay' just as recent storms put the Serranía de Ronda on high alert
There are coincidences that even a Hollywood scriptwriter could not improve upon. For 15 years, filmmaker José Luis Matoso has been obsessed with the story of the Presa de los Caballeros in Montejaque - a flagship 1920s project that became the most spectacular engineering disaster of its era.
Next Friday, Matoso premieres his docuserie, El Gato y los Caballeros (The Cat and the Knights), in Ronda. By a strange twist of fate, the "ghost dam" he spent over a decade documenting has suddenly clawed its way back into the present day.
Following the recent "train of storms" that battered Andalucíia, the dam filled to critical levels. The surge forced the evacuation of 200 residents in Estación de Benaoján to prevent a catastrophe. For Matoso, the timing is what he calls a "tragic relevance."
"My phone has exploded with messages," the filmmaker says with a smile. Having spent 15 years interviewing locals and studying the site, he is now the region’s de facto expert on whether the dam's wall will hold.
"The key question is if it will break. The engineers say no, and what I can add is that it was built by the best Swiss and German firms of the time. The arch design was pioneer work; it’s the ground beneath it that failed."
Matoso’s documentary, which debuts at Ronda’s Convento Santo Domingo at 4.30pm on Friday, traces the origins of the Sevillana power company's failed dream.
In 1923, Swiss engineer Heinrich Grumer arrived in the Serranía de Ronda to oversee the construction of an 80-metre-high concrete vault. It was a marvel of modern technology. But when the first rains came, the engineers watched in horror as the reservoir emptied as quickly as it filled.
After construction, the surprise was that the reservoir began to empty for no apparent reason. The answer was under the floor of the dam, where two caves ran: Gato and Hundidero.
The dam had been built on porous karst rock. Deep beneath the structure lay the Gato and Hundidero caves - massive underground galleries that acted like a giant drain.
The docuseries reveals a pivotal moment in local history: the scientific proof that the Hundidero and Gato caves were, in fact, the same cavity. To prove the theory, Grumer sent two teams of workers into opposite ends of the mountain.
The docuseries reveals the discovery that the Gato cave and the Hundidero cave were the same cavity. "There was suspicion, but not scientific certainty", reveals Matoso.
Among them was a 13-year-old local boy, Joaquín Guerrero. Matoso spent three months tracking down the boy’s descendants after reading a 1987 article in SUR.
"Joaquín had passed away, but he left a 30-page manuscript titled My Journey through the Depths of the Earth," Matoso explains. "It is the only first-person account of the discovery. He wrote that when the two groups finally met in the darkness and realised it was the same cave, they began to dance and sing flamenco."
Despite attempts to plug the cracks from inside the caves, the engineers eventually surrendered. Nature could not be tamed.
El Gato y los Caballeros' includes testimonies of the earthquakes that occurred when the dam was filled, such as those that have now occurred in Grazalema with the aquifers during the storm train.
The film also documents the "induced earthquakes" that occurred a century ago when the dam first filled - a chilling parallel to the tremors recently felt in Grazalema. Descendants of those who lived through the 1920s describe nine distinct quakes triggered by the weight of the water.
For Matoso, the completion of the film is a triumph of "artisanal" filmmaking over the conveyor-belt style of modern streaming platforms. Having produced the series without external funding, he is now considering how to distribute it.
"If necessary, I’ll set up my own platform," he says defiantly. Given that he has already conquered a 100-year-old engineering mystery and a 15-year production cycle, 'Matoflix' might not be far off.
