Marmara Lake

Marmara Lake is a freshwater lake located within the boundaries of Manisa Province in Türkiye’s Aegean Region, situated between the districts of Gölmarmara, Salihli, and Ahmetli. With an elevation of 74–80 meters and a surface area of 6,912 hectares, the lake has been transformed into a reservoir by a 5.75-kilometer-long natural dam on its eastern and southeastern sides. To the east of the lake lies Keçidağ, to the south the Salihli Plain, to the west Çal Dağı (1,034 m), and to the north the Gölmarmara Plain.

Geological and Morphological Structure

Marmara Lake is an inland water body formed within a tectonic depression of the Gediz Graben System, one of the active tectonic zones of Western Anatolia, and exhibits the characteristics of an alluvial dam lake.

The lake occupies a naturally closed depression with locally shallow basin morphology, shaped by the accumulation of alluvium carried by the Gediz River and Kumçayı. This depression is bounded by active faults oriented northwest-southeast. The area surrounding the lake is surrounded by various formations of the Menderes Massif. To the west of the lake is Çaldağ (1,034 m), to the east Dibek Dağı, to the north the Gölmarmara Plain, and to the south the Salihli Plain. The terrain is composed of diverse geological units including gneiss, mica schist, amphibolite, marble, crystalline limestone, marl, sandstone, grauwacke, radiolarite, and ophiolite. This complex geology has resulted in a highly varied and rugged topography around the lake. Particularly in the northwestern sector, abandoned marble quarries are the origin of the lake’s name. These quarries, referred to as “Mermere” by Evliya Çelebi, are located on a hill known as “Marmara Dağı,” from which the lake derives its name, Marmara Lake.

The formation of the lake is linked to subsidence processes active during the Pliocene and Pleistocene epochs. Alluvium transported from the north by Kumçayı and from the south by the Gediz River gradually accumulated in the low-gradient area between Salihli and Gölmarmara, forming a natural dam. As a result, waters ponded in the depression formed Marmara Lake.

The region’s climate (semi-arid to semi-humid) causes pronounced seasonal fluctuations in the lake’s water budget. Water levels rise during winter and decline in summer due to high temperatures and evaporation. This leads to significant annual variations in the lake’s water level and surface area.

The lake’s catchment area is approximately 1,780 km². The lake has no natural outlet, which has rendered it prone to salinization. However, from the 1930s onward, various artificial interventions—canals, regulators, and pumps—have altered these natural processes, transforming the lake into a seasonally managed reservoir.

Marmara Lake (Ministry of Agriculture and Forestry of the Republic of Türkiye)

Hydrological Characteristics

The main water sources are the Çömlekçi Regulator fed by Kumçayı, the Adala Regulator fed by the Gediz River, and the Ahmetli Pump Station. With a capacity of 320 million m³, the lake serves as the primary water source for irrigation activities in the region. Depending on the year, the lake’s surface area varies between 25 and 72.9 km², and its volume between 15.58 and 377.7 hm³.

Ecosystem and Biodiversity

Marmara Lake supports 162 bird species, 11 fish species, 26 algae, 6 zooplankton, 33 amphibians, 32 mammals, and 355 plant species. Among these are endemic species such as Ladigesocypris mermere, endemic to Türkiye, and Kripowitschia mermere, endemic to the lake. The lake serves as a breeding and wintering ground for bird species including the Dalmatian pelican (Pelecanus crispus), spiny-tailed lark (Vanellus spinosus), ferruginous duck (Aythya nyroca), and little bittern (Ardeola ralloides).

Conservation Status

In 2002, Marmara Lake was designated as a wetland under the “Regulation on the Protection of Wetlands.” In 2017, it was declared a Nationally Significant Wetland and simultaneously registered as a natural site. In 2022, it was reclassified into a buffer zone (24,893 ha), a sustainable use zone (1,495 ha), and a controlled use zone (552 ha).

Human Activities and Land Use

The area surrounding the lake is intensively used for agriculture and livestock farming. Crops such as watermelon, melon, cotton, and tobacco are cultivated. Both large and small livestock graze in the vicinity. There are 102 licensed fishermen and 51 registered fishing boats. Settlement areas experienced a 173% population increase between 1986 and 2011, while pastures and aquatic plant areas suffered significant declines.

Reservoir Function and Water Management

The lake was converted into a reservoir between 1938 and 1945 by the construction of a dam. From the 1950s onward, it began to be fed via irrigation canals connected to Kumçayı, the Gediz River, and the Ahmetli Regulator. Water release for irrigation is carried out through the Marmara Regulator, spillway, and discharge canals. Marmara Lake is used to irrigate approximately 40,000 hectares in the Gediz Plain.

Desiccation Process and Threats

Between 1975 and 2018, the lake’s surface area shrank by 43%. Particularly between 2011 and 2018, it contracted by 38%, and by 2021 the lake had completely dried up. Major causes of desiccation include climate change, water transfer projects based on the Gördes Dam, excessive irrigation, narrowing of irrigation channels for agricultural purposes, conversion of marshlands into farmland, and illegal fishing.

Ecological and Socioeconomic Impacts

The desiccation process has affected both biodiversity and the livelihoods of local communities. Fishing activities have ceased entirely, and agricultural productivity has declined in surrounding villages. The loss of the lake has contributed to regional aridification and disruption of the local water cycle.

Conservation and Monitoring Efforts

The Ege University Bird Observation Group and the Ege Association for the Protection of Natural Life conduct monitoring and inventory studies at the lake. Re-filling projects are under consideration by the State Hydraulic Works (DSİ) and the Ministry of Agriculture. Since 2021, scientists have been evaluating alternative water sources and nature-based solutions to restore the lake.