frogmandan 
Re: southern toad
It looks alright, but you difinatly need to give it more substrate, and more of an area to burrow. Also, I'd recommend going to your local pet store and 1. buying it a "Coco-hut" (it's a hallowed out coco-nut half shell that works great for a hiding place for them) 2. replacing the sand with coco-fibre/eco earth, as in that set-up with so much water & humidity, the sand will be stuck to the toad almost all the time.
You definitely need to add more rocks to the bottom, it's far to deep for that toad.
If I may offer you a suggestion;
The terrarium set-up you have now is okay, but for it to be 100% suitable for your toad, it will require many changes.
If you plan on keeping the toad, and you want it to be happy and healthy, I'd take the time (maximum if you have all the materials, 1 hour) and clean out the tank, remove all the aquarium gravel, glass stones, etc, add fresh substrate to the entire tank (no water section this time, just a water bowl), give it at least 4 hiding places, add some live plants (most vines such as ivy or creeping fig work well as ground cover, then some taller leafy plants can be purchased at most chain stores), and give it an appropriate sized water dish.
It's not that there's anything wrong with the water section you have, but toads arn't normally found by large flowing bodies of water, so this could be stressing it, toads do not "swim" like a bullfrog or FBT would, they simply sit in water to absorb it through their skin (they also to prefer calm water), it's their way of "drinking", and a water section takes up a lot of space and I know you said it was a 3:1 ratio, but that water section looks to be close to 50% (if not more) of the tank, so a large water section, with flowing water, is not necessarily benifical/needed to/for the toad.
To completly re-arrange your aquarium/terrarium you'd be looking at less that 20$ (10$ for substarte, 4$ max for two coco-huts and 5$ for a water dish), and once done, the toad would then be in an enviroment closer to it's natural habitat.
May I also ask, why did this toad need to be rescued? In most cases, they don't have to be rescued unless they are injured, if it's fine, again, why did it need rescuing?
If you do not want to care for it, you can release it back into the wild now, and it will survive, but if you keep it, THEN decide to release it, it will die because it has become used to the temperate range of indoors, being fed, etc.
Just some suggestions,
~Royce
P.S. If you do decide to rearrange it's terrarium, and plant live plants, make sure, before you plant them, throughly rinse off the entire plant, right down to it's bare roots so there are no pesticides/fertilizers left (if there were any on it, better be safe than sorry!) on the plant that could harm your toad.
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