RainLover wrote:

1 - How can I be sure the water will STAY PUT in the pond? The only
thing I can think of is to dig it and fill it before I do any
landscaping or detail work and see how it holds water. Is there a
better way?

I think that's probably the only way you can be _sure_ :-) You can do a
percolation test - dig little holes in the area you're going to put the
pond, and see how long they take to drain, but if they drain fast, it might
just mean you have a porous surface layer, and if they don't drain at all
it could be because you _don't_ have a porous surface layer but you'll be
digging through it to make your pond. In any event, most likely there will
be _some_ drainage - it's a matter of what you think is slow enough (and
remember that if you're pumping out subsurface water, you could eventually
drain your own well).

2 - Will I have to worry about the entire pond being overtaken by
natural plants? How deep should I make it to where most vegetation
won't just move in and take over?

I'm not sure depth will make much difference. Yes, local vegetation will
want to take over.
--
derek