At high water levels a small outlet stream appears at the northwest end, but it is absorbed into the ground after a short distance.

It is assumed that fine-grained densely compressed ash, basalt rock or a small permafrost layer may play a role.

On 26 September 2013, the lake had been reduced to a mere puddle of less than 2% of its original surface size, with a reported width of 9 m (10 yd) and maximum depth of 23 cm (9 in).

Aside from Poliʻahu, there are two additional snow deities, Lilinoe and Waiau, who are associated with Mauna Kea, and according to Westervelt, the lake was probably named after the goddess of the same, who used to bathe in it.

Originally Hawaiians considered the whole peak region of Mauna Kea, including Lake Waiau, a sacred site, and only priests and chieftains were allowed to access it.