Hu-lun Lake has varied considerably in area according to variations in the.... lake river.

At one time it was part of a large lake that included , a somewhat smaller lake situated in the south of the Hu-lun-pei-erh Plain, which drains into Hu-lun Lake via the Orxon River. It is comparatively shallow and is joined by a seasonal channel to the Hai-la-erh River, which flows into the Argun River. For much of the year, however, it is undrained, and occasionally, when its level is very low, there is a reverse flow of waters from the Hai-la-erh River into the lake. During the six months of bitter winter cold, most of the fish in Hu-lun Lake migrate up the Orxon River to Pei-erh Lake. lake river.