Thank you
@Old Hillwalker; I've only skimmed through the information so far but I intend to get back to it soon. I would like to supplement what you have posted though.
Walking the camino high above the Yesa you encounter blue painted stones. These
piedras azules are a form of protest and a call for action. They have been placed to mark the planned high water of an enhanced damming of the Yesa. It is this flooding that forced the abandonment of Ruesta. The stones show how the flooding will affect ruins and landmarks along the camino and the path of the camino itself. The full flooding may not happen during our lifetimes though as climate change is affecting the amount of water that reaches the dam (less) and also the amount of water that needs to be drawn off for use (more).
The project that is fighting the damming,
Yesa No, has a web page for the blue stones at
http://www.yesano.com/noticias2010/piedrasazules.html
(I've got to say,
Yesa No sounds a little weird to English speakers ears.)
Just a short ways past Ruesta on the camino you will come across a blue stone at the ruins of the Ermita de Ruesta. Google Maps has a link to the location and a few photos but I'll supply mine too.
https://maps.app.goo.gl/XXZ4trE5QCQEKQTU6
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