Over 20% of the lake's water comes from nearby Lake Prespa which is 150 meters higher than Lake Ohrid. The water leaves Lake Prespa trickling through underground watercourses where it is joined by mountain range precipitation and eventually emerges in numerous springs along the eastern shore and below the water surface of Lake Ohrid. The water leaves Lake Ohrid by evaporation (~40%) and through its only outlet, the Black Drin River, which flows in a northerly direction into Albania and thus to the Adriatic Sea.