Have you seen this?
http://www.ehow.com/farm-pond/I wish I could have a pond. There is one on the farm on which we live, about an acre or so in size, but it needs lots of planting for more wildlife. There are sticklebacks, and billions of frogs and toads in it, but no larger fish, despite there being abundant invertebrates. It's fed via a small temporary dam in the burn (as and when required), and has a deep water outlet via an adjustable sluice.
I have seen several species of ducks on it all year round, and it has seasonal visitors such as swans, little grebes, kingfishers, herons, and even the odd cormorant. Recently I found an otter spraint on a rock near the inlet, and sandy footprints in the end of the inlet pipe. I think an otter is running through the pipe when it is not in use.
Having a sandy edge in places, and gravel/chuckie stones in others, it is great for seeing tracks of other visitors. I've seen badger and fox prints, cats from the farm have left marks, and roe deer drink from it regularly. It seems to be a bit of a watering hole. Our horses drink from it too when they are in there.
The one downside to it is the steepness of its sides over much of its perimeter. In places it drops quickly into deep water and is probably about 1in5 in a few bits; too steep for planting, and it doesn't allow much for warm shallows which are liked by most pond dwellers at some time or other.
Friends of mine have a really nice pond in their large garden. It is fed by a tiny spring, at a fairly constant but slow rate, and they have created a bog garden at the outlet, where it soaks a large area of one side of the pond and just dissipates from there. They have planted wild species and some complimentary cultivars, and they even have some goldfish in it which have bred successfully some years.
Having young children, it has always been difficult for me to commit to a pond in the garden, so we have a Belfast sink. It has a large-hole weldmesh grid over it, and we have some Iris and spiral grass in it. The kids get spawn from the big pond and grow frogs and toads. Nothing ever spawns in the sink, though, so I wonder if adult frogs go back to their pond of birth even having been reared elsewhere. We put whitecloud mountain minnows in it in the summer as they eat any mosquito larvae which may arrive.
Now the kids are a bit more able, I am thinking of a garden location to have a raised pond with a bit of running water...I'm away out for a look.
Shearling...I don't know about regs, but I think there are some considerations to do with diverting existing watercourses, especially if the water continues back to source after servicing the pond. SEPA (in Scotland) will probably have some say in that.