Istanbul’s Water Supply: Dam Levels Dip Below Expectations
Istanbul Drought
Despite the arrival of April showers, Istanbul’s water supply in 2026 remains in a precarious state. According to the latest data from the Istanbul Water and Sewerage Administration (İSKİ), the city’s overall dam occupancy rate has struggled to break past the 70% threshold. On April 20, 2026, measurements showed a slight regression back to 70.36%, sparking fresh warnings from experts about a potentially difficult summer ahead for the megacity.
Current Dam Occupancy Rates (April 20, 2026)
While some dams on the Asian side show healthy levels, others, particularly those serving the European side, are significantly below capacity.
| Dam Name | Occupancy Rate (%) |
| Ömerli | 92.89% |
| Darlık | 86.80% |
| Elmalı | 91.54% |
| Alibey | 67.47% |
| Kazandere | 61.01% |
| Pabuçdere | 61.06% |
| Terkos | 57.16% |
| Büyükçekmece | 56.65% |
| Sazlıdere | 45.36% |
| Istrancalar | 40.12% |
Why 70% is Not Enough
Experts point out that five years ago, Istanbul’s dam levels were consistently around 90% during the spring months. The current 70.36% is considered insufficient for several reasons:
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High Consumption: Istanbul’s daily water consumption exceeds 3 million cubic meters.
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Decreased Natural Feed: Reduced winter snowfall and lower river flows have weakened the natural replenishment of the basins.
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Urbanization: Rapid urban expansion continues to shrink the natural catchment areas of the water basins.
The Melen and Yeşilçay “Lifelines”
Istanbul’s existing dams can no longer meet the city’s annual demand of approximately 1.5 billion cubic meters on their own. The city has avoided a severe water shortage primarily due to external transfers.
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External Support: So far, 267 million cubic meters of water have been transferred from the Melen and Yeşilçay systems.
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The “Can Simidi” (Lifeline): These external sources act as a critical buffer, preventing the city’s reserves from dropping to critical levels during high-demand periods.
A Difficult Summer Ahead
Prof. Dr. Meriç Albay warns that even if Istanbul’s dams were at 100% capacity, they would still struggle to meet the city’s massive annual demand without external aid. With the peak evaporation season approaching in the summer months, the current stagnation in reservoir levels suggests that water conservation will be paramount for residents.