[myvada]

I have an area of land which has water draining through and some parts are boggy,there is a stone shed on it ideal for shelter. Can the ground be too wet for pigs, can it cause health issues.

[HappyHippy]

Yes, it can cause arthritus in the longer term, but even for raising weaners to slaughter it can turn into a very muddy mess - VERY QUICKLY ! 
You've not said how big the piece of land is, but if around 50% of it is dry and the rest wet it could be okay for weaners during the spring/summer providing you don't overstock the pigs.
HTH
Karen