Caught very young Garter in basement what to do?

[guidofatherof5]

Craigslist is a good place to pickup free aquariums. Just be sure to clean them out good with bleach/water mix.

[d_virginiana]

I probably wouldn't bother with a permanent setup in this situation. I keep several clear tupperware containers with air-holes poked in them for short-term rescue/rehab reptiles; easy cleanup and cheap.
If you don't plan on keeping it, the best thing would be to just let it go sooner rather than later if there are no injuries. Seems like it's already had time to drink water if it was dehydrated. There's plenty of time before winter for it to get food and find a place to hibernate. One thing I'd definitely advise against is keeping it over winter then releasing it in the spring since there's no medical reason to do so.