When we had a place at El Campello in the 80's, the ley de costa's was all the go. I remember some time (around 87/88, the then mayor of Elche won huge public acclaim being photographed in the press pushing the detonator & demolishing a half-built skeleton of concrete that was in contravention.
Since then I'm afraid, less gets enforced, & plans to demolish illegal stuff close to the high water mark seem to have gone out of the window