[1] The lake is named after the Qilu mountain (nowadays called Xiushan), directly south of Tonghai county seat.

During the Yuan dynasty, the lake used to be larger and reach up to the base of this mountain.

The lake has no outlet rivers, but water can leave the area through karst caves.

[3] According to local legend, the area around the lake used to be flooded and was called Tonghai.

A monk used a shippei to make a hole in the lake bed and allow water to flow out.