Perhaps

We may, repeat, MAY, luck out.
The water leak appears to be in an incoming water line to the water heater, not the heater unit itself.  Was not easy to see, not at all.  I have done some "rigging" of what passes for a system in this place.  Hope to turn system on shortly after further examination.
Now, FYI, I believe this is the FOURTH such instance in that system.  The unit is in an area we rarely enter, so the length of time of problem is unknown.  I can confess to mildew in the room, and some damaged sub flooring.
But it could have been worse.