In the southern Prokletije, the Drin dominates. It drains most of the ranges with its tributaries and when measured from the source of the White Drin in Radavc to the mouth of the Drin near Lezha, it is long. However, not all of the Drin flows near or parallel to the Prokletije. One Drin tributary is the Valbona, which drains into the Adriatic Sea, and its eastern tributary the Gashi River. To the west of the Prokletije is the Cijevna, which drains the northwestern part of the Montenegrin-Albanian border area to the Adriatic. Water levels fluctuate due to the karst hydrological drought in the Prokletije. Some rivers or streams, such as Përroi i Thatë in Albania, dry out completely during the summer droughts. Although the Pećka Bistrica in Kosovo is short, it is very powerful and carved the Rugova Canyon.