The place to site a pond is a spot where it is perfectly level. The more level the pond, the less rock you will need to hide the liner.  Don't just eyeball it.  Get out some stakes, string and a level.  Take my word for it--you'll be surprised at how "not level" your yard really is!

Even when you do find a level area to site your water feature, you will still require a large amount of native stone (especially if you plan a waterfall), so start looking around for a source. I got mine from someone who was building a house next to a shale hill. He was more then happy to get rid of as much rock as my husband and I wanted to haul out.

If you want your water plants to bloom profusely, they will need at least five to six hours of direct sunlight. Start watching your yard for the light patterns. If you wait until the winter to start planning, the trees won't have leaves and the sun is much lower in the sky. Take a few notes so you have a good idea later where the summer sunlight falls and how long.

It sounds like a lot of rules, but some can be broken. I sited my water garden on a slope under the shade of a large pine tree. I didn't have another area more suitable, so I'm willing to work around the negatives. As a result, I spend a lot of time fishing for pine needles and my water lilies never bloom as freely as they would if they had more sunlight. Because it was lower on the bottom side of the pond, I also had a heck of a time getting the sides level so that my liner wasn't exposed to the elements.  On the positive side, the waterfall looks beautiful cascading down the natural slope into the pond and I don't get as much algae as those who have ponds in full sunlight. [Note: If you have a problem with algae and don't want to use harsh chemicals, many gardeners have had good luck using barley straw in barley strips, barley balls or barley pads to keep their water clearer.  For more information, read the article "Barley--the Secret to Clear Water"]

Once you have decided on the perfect location for your water feature, take a hose and lay it out in a natural shape. To calculate the amount of liner you will need, take the length and width of the pool and add double the maximum depth (usually 18 to 24 inches), plus two extra feet on each side for overlap. (Hint: Once it is time to actually cut the liner--DON'T. Most--including myself--make the mistake of cutting the liner too short.  Instead of cutting, just fold the excess under rocks. That way when things settle, you have the latitude to add the excess liner.)

By all means if you can't decide how big you'd like your pond--err on the larger side. After the hole is dug and the liner installed, it is too late to go bigger without a lot more labor and expense. This is one of the reasons I recommend waiting a season to start this project. It will give you time to contemplate which and how much liner you need, how big a pump and which plants to grow.

I can't imagine a pond without moving water. If you would like to have a waterfall, but don't have a slope next to your chosen area, build one up with rocks and fill from the excavation. Make sure when you order your pond liner you get enough to entirely line the course of the waterfall. You'll also need a pump to recirculate the water from the pond back up to the top of the waterfall. We attached car radiator hose to the pump (my husband's idea) which has been buried for over five years and never sprung a leak. If you use regular clear tubing, place it inside rigid PVC pipe for protection when you bury it.

There are many good books on water gardening as well as web pages such as the International Waterlily Society, the Minnesota Water Garden Society or the GardenWeb Pond and Aquatic Plants Forum or the article on Water Gardening at Gardeners Supply. If you do your homework this season--you can spend next summer listening to your waterfall and watching the goldfish.