Answer: Building a pond is a big venture, so I suggest you do some research before you begin digging. You have several options for lining a pond--some people use plastic, others use a layer of clay, etc. It all depends on your soil, where the water is coming from, where your water table is, etc. Here are two good books to look at:
Earth Ponds : The Country Pond Maker's Guide to Building, Maintenance and Restoration, by Tim Matson
The Pond Doctor: Planning and Maintaining a Healthy Water Garden, by Helen Nash
You might want to call in a professional landscaper with experience building ponds--at least for an initial consultation to get you started. I hope this helps.Good luck!
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