Naturally fed pond in garden

[blade7]

Not in my garden, but I'm wondering if there's likely to be any problems with quite a big naturally fed garden pond that has filled in with rocks and gravel ?

[blade7]

OK, a vacant house we were close to buying a few months back used to have a fair sized naturally filling pond in the front garden, we only found this out after speaking to neighbours, as it has been filled in with rocks and gravel apparently. So the water is probably still there, is it just wet rocks and gravel now or are there likely problems waiting to happen ?

[blade7]

The neighbour has lived there for 30 years and said in dry spells the water level used to drop a lot, I'm guessing the point in using rocks and gravel to fill it was to avoid a bog, and the pond is effectively still there ?