Wikipedia
Dew pond
A dew pond is an artificial pond usually sited on the top of a hill, intended for watering livestock. Dew ponds are used in areas where a natural supply of surface water may not be readily available. The name dew pond (sometimes cloud pond or mist pond) is first found in the Journal of the Royal Agricultural Society in 1865. Despite the name, their primary source of water is believed to be rainfall rather than dew or mist.
Usage examples of "dew pond".
The screen of osiers parted and we were looking down a steep bank to a dew pond.
And there was a spring, or rather a dew pond, filled with clear, sweet water, set in the island's center and surrounded by tall ferns and sweet-smelling flowers.