There are a total of eight water galleries, 6 driven into the slopes of Montaña Guatisea and 2 more in Montaña Blanca. They supplied water to Tías and San Bartolomé and are a testament to the islands hydraulic engineering.
Work began in the 1940s during the Franco regime (1938 -1973). Many of the locals worked as day labours, long hours, with nothing but hand tools. Franco also forced prisoners to work on the construction project.
There are 6 chambers hewn out of the lava of Guatisea, about eight meters high, four wide and twenty deep. The two chambers of Montaña Blanca are larger. Collection channels are chiselled out of the volcanic rock to feed run off into the cisterns.
The last of the Water Galleries at Guatisea were completed in the early 1960s. A series of sluices and pipes directed the water into the centre of Tias and San Bartolome. Where it was distributed by a local guard.
There is a stone monument at the Guatisea site paying tribute to Franco, but it has been mostly obliterated by hunters shotgun pellets.
The website of the original Spanish source material can be found here.
Walks In The Area
There are a number of hiking trails in the area, but two of my favourite circular walks are: