Your comments were great regarding the issues with the waterfall/pools freezing:
no water for the bears to drink, concerns ice would fall on bears or staff, ice might pull rock down as well, pump burning out because of lack of circulation of water, pipes bursting do to frozen water, bears slipping on the ice or falling through.
The other thing we did was lower the water level in the moat by a couple feet- do you know why?
Two thoughts come to mind. One, to prevent the bears from walking out onto the moat and getting out, and two, to allow for the expansion of the water as it cools and forms ice.
So that the bears can't walk across the ice and out of their enclosure.
you got it.- we don't want our bears leaving.