I live in coastal NC, where there are swamps, sandhills, and pocosins and even a few hot springs.
I'm moving to go to graduate school in 3 weeks now - if I get done with my packing and have a few days free I'll definitely take trips to all the local water holes and take pics for you.
But first, let me tell you about one pond that I love. Its a large pond, about 2 acres large I'd guess. I suspect it might be spring fed, but that doesn't stop it from drying up when there's a drought.
I looked on microsoft maps and found it, apparently a dry square in the pine savannah. On yahoo maps it shows as being filled up. Go figure.
This summer its been half filled. There's differing elevation in it and so some parts are dry and some are still wet. I'd say that its about 5ft below full level right now. Also, even though its in the sandhills the actual substrate is a white-grey sand-clay mixture. Most of the surrounding substrate is a loose sand with bits of organics. The pocosins located nearby are usually peat.
The water is mostly clear, with a visibility of about 5ft, and then it turns a green-blue. This is fine for the plants, since currently all the submersed plants are no more than 1ft below the waterline, although extending up to the dry shore you can see eriocaulons and eleocharis in various stages of drying out.
Last time I was out here there was little algae, but now a loose scum and bit of spirogea is starting to grow around the submersed plants. I walked out a bit, being careful to walk in the deeper areas around the plants. Its really beautiful out there as I can see several species of fish darting about, and even a school of small fish, <1cm long, along with frogs and plenty of water bugs.
I have to remember to catch a boatman.
A white heron also decided to visit while I was out there.
Anyhow, I suspect its spring fed because there are a few >10ft deep areas that you can see large holes inside, almost like mini caves.
I apologize for not having the foresight to take my camera, but I did take a few eriocaulons and eleocharis that were loose and floating (I swear that they were already uprooted and floating). A few handfuls of muck later I also decided to snag some droserea that were growing on the shore as an experiment.
The water level in this tank is actually deeper than the water level that the plants were growing in.
PS, I also didn't have any sample vials on me, I swear I'll take some with me next time too and analyze the water.
Two years ago I visited here and took some Eriocaulons for taxonomic research. If I remember correctly there are Eriocaulon compressum and Eleocharis vivipara. (I hate E. vivipara as an aquarium plant, but since this is a bit of home that I'm taking with me I'll deal with it!)