Lake Durusu's origins are in the sea. It formed as a coastal lagoon, gradually cut off from the Black Sea by the accumulation of sediment and the shifting of the shoreline. The narrow barrier that now separates the lake from the sea is a remnant of that process. Without a connection to the salt water, the lake has been fed instead by creeks — the Istrance creek being the most significant — draining a basin of 619 square kilometers of Thracian countryside.

The result is a lake of considerable depth and capacity, set in a landscape of low hills and pine-oak forest typical of European Turkey. In ecological terms, it functions as a freshwater system: reeds and wetland vegetation fringe its shores, and the combination of open water, marshland, and forest makes it productive habitat for birds. It is listed as an Important Bird Area of Turkey, and waterbirds use it in significant numbers during migration seasons.

The village near Lake Durusu has a recorded history of roughly 900 years. In the medieval period, the lake and its surrounding coast had a rougher reputation: the area around the lake was, according to historical accounts, a settlement for pirates who operated in the Black Sea. The geography supported this — a sheltered position behind the coastal barrier, close to sea routes but screened from casual observation.

The Genoese, whose commercial empire spread across the Black Sea in the medieval centuries, built a monastery near the lake called Trikos — a name that survives, transformed into Terkos, as one of the lake's alternative names. The monastery represented a more settled use of the location. By the 19th century, the lake's character had shifted again, becoming the focus of Istanbul's early municipal water engineering.

Istanbul's population in the 19th century was placing demands on its water infrastructure that the ancient Byzantine cisterns and Ottoman fountain systems were not designed to meet. Engineers and officials looked north and west for solutions. Lake Durusu, with its substantial freshwater capacity and its proximity to the city — relatively speaking, in a pre-automobile era — offered a practical answer.

In 1868, the Ottoman government granted a concession for the lake and its surroundings to an Ottoman-French company. The concession authorized the development of water supply facilities that would draw on the lake and deliver water to the city. Samples and studies confirmed what practical observation suggested: the water was suitable for drinking. Infrastructure was built. The lake became formally integrated into Istanbul's water supply system, a role it has continued to play for more than 150 years.

The Istanbul Canal project, announced in 2011 and begun in preliminary stages in 2021, would eliminate Lake Durusu entirely. The planned canal route passes through this part of Thrace, and the lake lies directly in its path. Opponents of the canal — including Istanbul's city government and a coalition of environmental and civic groups — have made Lake Durusu's fate central to their argument. Removing the lake would eliminate the water supply it provides: roughly a fifth of Istanbul's drinking water, drawn from a basin that has no ready substitute.

The environmental impact assessment prepared for the canal project did not, according to a scientific review commissioned by the Istanbul Metropolitan Municipality, adequately address the risk to the Terkos Dam and the groundwater systems associated with it. Critics also noted that salt water intrusion from the canal's connection to the Black Sea could compromise the freshwater systems in the region. The fate of Lake Durusu remains contingent on the fate of the canal — a project that, as of this writing, has begun construction on at least one component but has not advanced to the stages that would affect the lake directly.