Your frog question is not strange at all, and I’m glad that you are concerned about the welfare of the frogs that were attracted to your water feature. Here are some things to consider:
I don’t know how deep your 100 gallon basin is, but if it is at least 20 inches deep, the water will likely not freeze all the way to the bottom if the basin is set into the ground (as opposed to an above-ground water feature). You could keep a re-circulating pump in the basin to discharge water at the surface and keep a hole open in the ice during the winter. (I actually do this in my own water feature.)
Also, if there is not sufficient substrate in the basin (muck, leaves, etc.) the frogs may not consider it a suitable place to overwinter and may go elsewhere.
In any case, don’t worry about them too much; these critters are much hardier than we think. Frogs have an amazing ability to find these little habitats, and new frogs will likely re-populate your water feature next year. That old saying “if you build it, they will come” is true!
I hope this has helped. If you have more questions, just email me: email@example.com.
-Naturalist Linda Gilbert