So, what's this then?

Looks like an old valve to some sort of underground water system

 

Relief valve for an aquifer - I only found out myself last year. When I am back on a PC tomorrow, I will try and find some more detailed information

 

I cannot for the life of me find it, but it was during the floods (year before last now? Time flies...) - they were interviewing someone about groundwater levels on the TV and they had these things dotted around as well as things that were basically pipes sticking up vertically, with a heavy flat metal plate for a lid bolted down/ Part of the interview showed them unbolting the lid which they said was to allow them access to measure the water levels (they were so full at the time, as soon as they started to unbolt the lid the water was gushing out).

If I remember correctly, the water in the aquifers were drawn off for water supply as needed, but if there was too much water in the aquifer it would result in pressure on the infrastructure that was used to draw the water, so it had to be relieved somehow - - to where, I have no idea as I would have thought that simply letting it drain onto land would have seen it soak back down into the aquifer?

 

There are probably valves like this all over the country that are accessible by the public - it is a wonder that there hasn't been incidences of people tampering with them and washing villages away

 

Why not??..............the Isle of Man Water Board will have archived plans of the island's previous water systems, and when that valve was installed "things" were probably different then

 

If I am right, it would have next to sod all to do with the river, other than the river being the 'safe' escape route for released water. Underground aquifers are absolutely massive - billions of gallons for some - in the event that the aquifer was overfilled, or about to be overfilled, this valve could be opened to divert the water into the river and let it get away, rather than have it enter the water supply infrastructure at a pressure where it would do serious damage. The houses are almost certainly completely unrelated also

 

It might actually control an outlet to the river, Sheal. Or it might be a controlling valve of a water system that can run and run for miles.