Your frogs won't drown in a water way as long as they have some kind of egress if the water is deep. Although they aren't aquatic, they can all swim well enough to get out onto a gentle slope or submerged log, according to Patrick Nabors previous advice to me. My galacs take an accidental bath in the aquarium portion of their paludarium every once in awhile. They like to try fishing for floating fruit flies and occasional tiny fish fry, and get over-enthusiastic. I have submerged logs in it that lead back to land, so they just swim over and climb back out. The only harm is to their dignity.
It looks like a good start on your vivarium.
Patty
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Patty
Lost River, Idaho
D. auratus blue
D. galactonotus
D. imitator
D. leukomelas
D. pumilio Bastimentos (soon)