Cathy, you have a beautiful yard there and quite a talent with the camera, as well as gardening and landscaping, but I'm sure you already know that.

I wish the pictures on your website would display larger, though, so I could see a bit more detail as to exactly how you're thinking about going about this two-pond system.

First, your current "dry creek bed" looks great, and I see you have it surrounded by a variety of perennials which no-doubt benefit from the water that seeps through those rocks when it does act as a drainage area... As for contamination in your pond system, if you build your lower pond there, you'll likely have to remove all the rocks to start with, in order to keep your liner from being constantly punctured. You could try to do it without a liner, using something like Bentonite clay, or a compound such as gunnite, but those are both beyond my level of experience...

Either way, if you build it where it DOES still get some runoff, yes, it will get "polluted," but not necessarily "contaminated." I have a two-pond system with a 55-foot stream between them, and unfortunately my lower pond sits where runoff sometimes overwhelms it when we have heavy downpours (I'm still working on redirecting that after three years -- we had gone MANY years without such heavy rains when I built it, and I had forgotten we got such rivers in our yard until I got to see my liner floating up from water going underneath it firsthand!)... The things you learn the HARD WAY, huh? :)

Anyway, even when mine just gets runoff IN IT, and not under the liner, I end up with a brown, muddy-looking pond for a day or two, but it clears -- BUT I don't use any chemicals in my lawn and nothing but some liquid fertilizer on my flower beds... If you have pesticides, herbicides, roof shingles that are leaching chemicals and whatnot UPstream of your drainage, those could all be concerns if you put fish and/or plants in your ponds.

My biggest question, however, is exactly where and HOW you plan to implement the larger pond ABOVE the dry creek bed, as from the pictures I could see, your yard appears fairly level on both sides of that dry creek bed, and of course you'd need a few feet of incline for the "upper pond" to be above the "lower pond," unless, perhaps, you're thinking of putting something on the deck that cute cocker spaniel was sitting on.

That's a possibility... It would have to be more of a tub-pond, like maybe a converted hot-tub, or possibly a preformed pond fitted into a structure you built, but it can be done IF the deck is sturdy enough to hold the weight (bear in mind that water weighs about 8 pounds per gallon and there's 7.5 gallons per cubic foot, so you can have a ton of water pretty quickly... roughly 250 gallons equals a ton).

But if you have the time, the money, the patience and are willing to do your homework ahead of time AND/OR make sure you hire people to do the work who REALLY KNOW WHAT THEY'RE DOING (there are PLENTY of folks doing this who DON'T), I think you can do pretty much anything you want to.

Best of luck to you!
Jeff

Thanks Jeff for the nice reply.
The yard is about a foot higher than the drycreek so it wouldn't be a big difference. I hadn't thought of using the deck as an "upper pond". There is a hot tub on the deck that we haven't used because the pipes have a leak. I can't quite picture what you had in mind, but I'm sure that I won't sleep thinking about it. This stuff has a way of becoming an obsession ;-)
Cathy

I haven't done it, but I know SEVERAL PEOPLE on this forum HAVE converted hot-tubs into above-ground water gardens, with one advantage being that you already know whatever they're sitting on will hold them.

You probably should make a posting titled "How do I convert a Hot Tub to a pond," and I'd do it on the Discussions forum, not here on conversations, where very few people come for serious pond talk. Most of the folks who are regulars in Conversations ARE experienced ponders, we just represent a small percentage of the total who visit and post to the Discussions area, and people looking to help folks with pond construction don't look for such postings in Conversations.

Good luck!
Jeff