Tortum Lake

Tortum Lake is a natural landslide-dammed lake located within the boundaries of the Uzundere district in Erzurum province, in the Eastern Anatolia Region of Türkiye. Situated in the transition zone between the Black Sea and Eastern Anatolia regions, the lake is of natural origin both in terms of its geological formation and environmental characteristics. Tortum Lake extends approximately 8.2 kilometers in length and 1.4 kilometers in width along a southwest-northeast axis and lies at an elevation of 1010 meters above sea level. With a maximum depth of 95 meters, the lake’s surface area is approximately 6.5 km². At normal water level, its volume is 57.6 hm³.

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Tortum Lake was formed at the end of the 17th century (approximately 350–370 years ago) when a massive landslide from Mount Kemerli blocked the valley of the Tortum River. The waters accumulating behind this natural dam formed the lake, while excess water flowed northward through the Tev Valley to create the Tortum Waterfall. The main body of the lake consists of landslide materials, while its shoreline and underlying structure are composed of Jurassic-Cretaceous age clayey limestones, sandstones, and volcanic rocks. The physical properties of these rock formations significantly influence sedimentation processes around the lake.

The lake lies within a basin enclosed by steep and narrow valleys between Mount Mescit (3230 m) and Mount Kargapazarı (3045 m). Due to sediments carried by the Tortum River, the lake is subject to active sedimentation from the southwest. A large delta has developed between the Cizirik and Beşkardeşler hills, where annual accumulation of 3,695,106 tons of suspended sediment and 596,000 tons of coarse sediment has been recorded. This process leads to a reduction in the lake’s volume and a gradual shift of the shoreline toward the lake center. The majority of sediment transport occurs via tributaries such as Bağlar, Vihink, Hınzorik, Liskav, and Mususin streams in the upper catchment area of the lake.

Tortum Lake lies within a transition zone between the humid climate of the Black Sea and the continental climate of Eastern Anatolia. In Uzundere, the average annual temperature is 9.29 °C with an average precipitation of 307.7 mm; in Tortum, these values are 8.19 °C and 468.7 mm respectively. Spring snowmelt increases streamflow and intensifies sediment transport. The surrounding area supports forested regions dominated by species such as Turkish pine, oak, and juniper, while lower elevations feature steppe and Mediterranean-type plant communities.

Tortum Lake faces environmental threats from overgrazing, illegal logging, and sand and gravel quarries. Uncontrolled sediment accumulation alters the lake’s morphological structure, causes shoreline retreat, reduces biological diversity, and endangers its hydroelectric, recreational, and ecological functions. For these reasons, the lake and its surroundings were declared a first-degree natural protected area in 2000, and its boundaries were expanded in 2002 to enhance protection.

The lake was integrated into energy production with the completion of the 26 MW Tortum Hydroelectric Power Plant in 1960. In addition, a 1.5-meter-high and 35-meter-long concrete dam was constructed at the lake’s outlet between 1971 and 1972 to regulate water flow. A portion of the lake’s water is also diverted to feed the Tortum Waterfall. Settlements, small-scale agricultural areas, and picnic zones are located around the lake.

Rich folk traditions surround Tortum Lake and the Tortum Waterfall, offering mythological explanations for their natural formation and preserving them as integral elements of local cultural identity. Below are the main examples of these legends:

According to the most widespread legend, the name Tortum derives from a remarkably beautiful girl. It is said that Tortum, the daughter of the Ağcakale Bey, gained fame throughout the region for her beauty. Despite prolonged requests, her family refused to give her to the bey’s son, who had fallen in love with her. One day, a brave young man disguised as a merchant arrived in Üngüzek, brought gifts, abducted the girl, and took her to the bey’s son. Shortly after their marriage, the young woman fell ill and died from sorrow and longing. Before her death, she bequeathed that her name be given to the land. Thus, the region came to be called “Tortum.”

In another folk tale, a shepherd from the Hars (Uludağ) village of Uzundere heard a voice saying “Geliremm” three days in a row while tending his flock. Finally, he consulted the elders of the village, who advised him to respond on the fourth day: “Come then, what will you do?” Immediately after speaking these words, a portion of the mountain broke loose and blocked the Tortum River, forming Tortum Lake. The excess water flowing over the barrier created the Tortum Waterfall.

In another version, a beautiful girl living in the wealthy village of Hasköy at the foot of Mount Kemerli went every night to fetch water from the stream. One night, she heard a voice cry “Get out, I’m coming!” and replied, “Come then, what will happen?” At that moment, a landslide detached from the mountain and swallowed the village. The lake formed, and the waterfall emerged.

In this legend, a shepherd grazing his animals on the mountain noticed a rock slowly shifting from its place. He reported the danger to the village lord, who dismissed his warning. One day, the mountain collapsed with a great roar, burying the village. Only a few people who were outside at the time survived. When it became clear the shepherd had spoken the truth, the cruel lord, who had previously tormented him, was struck by divine retribution and died. This event is linked to the formation of the lake.

According to this tale, a shepherd tending his flock on the mountain heard in his dream the warning “Get out, get out!” Upon waking, he told the villagers, but no one believed him. He took his herd and left the village. The next day, a major earthquake struck, burying the village beneath the mountain. The resulting landslide formed Tortum Lake, and the flowing water created the Tortum Waterfall.