What's this blue at Upper Dean Head reservoir, Halifax?

[MitchT]

Someone I follow on Facebook took this with a drone. It's above Upper Dean Head reservoir near Halifax in West Yorkshire. I'm curious as to what the bright blue is...



It's visible on Google too (right side of photo)...



I'd go and check it out but it's a complete pain to get to. I've searched online but I can't find an explanation.

[andburg]

perhaps some charity colour run where they throw paint powder at you as you go?

[vaud]

MitchT said:

Someone I follow on Facebook took this with a drone. It's above Upper Dean Head reservoir near Halifax in West Yorkshire. I'm curious as to what the bright blue is...

You/they might want to ping it to Yorkshire water for their decision to look into it.