Lake Ohrid is located between the borders of Macedonia and Albania. It is one of the deepest and oldest tectonic lakes in the Balkan peninsula and is situated at an elevation of 695 meters above sea level. Lake Ohrid is about 18 miles (30 km) long and 9 miles (15 km) wide. With its unique flora and fauna from the Tertiary period, the lake is one of the greatest biological reserves in Europe. Most of its plant and animal species are endemic and unique. In 1979 the lake was declared a World Heritage site by UNESCO. Most of Ohrid's water comes from Lake Prespa, which is located on the other side of Mountain Galicica. Due to the high elevation, Prespa spills its water down to Ohrid throughthe two mountain springs Ostrovo and Biljana, located near the monastery of St. Naum and Ohrid, respectively.