Tim Matson is the established guru of building ponds with an earth-seal, rather than with a plastic or concrete lining. For 30 years he's been creating, advising, and collecting knowledge about pond-making. His classic Earth Ponds (2nd ed.) is the basic how-to, and comes with a DVD. It supplies the needed lessons in siting a pond, building it, maintaining it, enjoying it, and also restoring old ponds. This is not your average how-to; it's beautifully written and a joy to read. If you find the basics to your liking and need more, Matson has an updated Sourcebook with plenty of resources, and an illustrated encyclopedia of pond variations and building techniques. Finally, Matson has a helpful website with more videos and sources.