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- October 12, 202619°
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- INTEREST37.00%-1.00
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- October 12, 202619°
Summer Pressure Increases on İzmir Reservoirs, Decline Accelerates at Gördes
While reservoir levels in İzmir have been declining since early June, the drop at Gördes Reservoir has drawn attention. Underground wells are becoming prominent in the city's water production, while efforts continue to protect Tahtalı Reservoir.
The June melt has taken on a new dimension at İzmir's reservoirs. The active capacity of Tahtalı Reservoir has dropped to 53.92%. Since early June, when it was at 54.48%, there has been a 0.56-point decrease over 10 days. The most striking development occurred at Gördes Reservoir, which had remained steady at 41.22% for a long time but today experienced its first significant drop to 40.69%.
On June 9, 176,000 cubic meters of water were drawn from Gördes Reservoir, making it the top source among all water production resources with a 25.3% share.
İZMİR RESERVOIR FILL RATES (JUNE 10, 2026) Tahtalı Reservoir: 53.92% Balçova Reservoir: 88.48% Ürkmez Reservoir: 97.55% Gördes Reservoir: 40.69% Alaçatı Kutlu Aktaş Reservoir: 71.39% İZSU BURNS GÖRDES WHILE PROTECTING TAHTALI İzmir's daily water production data clarifies İZSU's summer strategy.
With a total daily production of 697,000 cubic meters, Gördes Reservoir is the largest source at 25.3%, while Tahtalı has fallen to third place with 17.3%. Underground wells alone meet 53% of daily production. This distribution reflects the lesson İZSU learned from last summer's harsh experience.
After the water crisis caused by the rapid depletion of Tahtalı Reservoir in 2025, Gördes and underground sources have been prioritized this year, while Tahtalı is being preserved as much as possible. The high volume of water drawn from Gördes Reservoir beginning to impact its level shows the limits of this strategy. The 154.8 million cubic meters of usable water in Tahtalı is 3.9 times the 39.5 million cubic meters available on the same date last year.
The total stock of 358.6 million cubic meters across all reservoirs, divided by the daily production of 697,000 cubic meters, corresponds to approximately 515 days of water security. Since mid-May, Alaçatı has lost 4.4 points in fill rate. With the rapid increase in summer population on the Çeşme peninsula, this decline is expected to continue. RESERVOIR FILL RATES BY CITY WHY IS FILL RATE IMPORTANT?
İzmir experienced six months of nightly water cuts last summer. During that crisis, water had to be drawn from the dead volume of Gördes, the unused Güzelhisar line was repaired, and underground wells were renewed. Despite all these efforts, only 28% of the water demand was met. Although this year's figures are much higher than last year's, reservoir levels during summer are being closely monitored.
WHAT DOES FILL RATE MEAN?
The fill rate is calculated by dividing the water accumulated in the reservoir by the maximum capacity the reservoir can hold. Rainfall and snowmelt increase this rate, while consumption and evaporation in hot weather reduce it. İZSU shares this rate as active fill, excluding the dead volume at the reservoir bottom that cannot be used.
WHY DO TOTAL FILL AND ACTIVE FILL DIFFER?
Each reservoir has a layer of water at the bottom that cannot be pumped and transferred to the network, called dead volume. Total fill rate includes this part, while active fill only covers the water that can actually reach taps. Since İZSU shares data based on active fill, İzmir's water situation is accurately reflected.
WHAT DETERMINES İZMİR'S WATER SECURITY?
Tahtalı Reservoir remains the city's largest single reserve with 154.8 million cubic meters of usable water. Following last year's crisis, the contributions of Gördes Reservoir and underground wells have also increased significantly. Whether this strategy reduces pressure on Tahtalı will become clear by mid-summer.
WHAT HAPPENS IN İZMİR WHEN RESERVOIR LEVELS DROP?
When Tahtalı Reservoir's fill rate fell below 10% in 2025, night-time water cuts from 11:00 PM to 5:00 AM began in 13 districts and lasted six months. İZSU took extraordinary measures to manage the situation. Despite all efforts, only 28% of the city's water needs were met. Declining water levels in reservoirs could force İzmir residents to face similar scenarios again.
WHAT PURPOSES DO THE RESERVOIRS SERVE?
Tahtalı, Gördes, and Balçova reservoirs directly produce drinking water. Alaçatı Kutlu Aktaş Reservoir supplies both drinking and irrigation water to the Çeşme peninsula. Although Güzelhisar Reservoir is primarily for irrigation, it can support drinking water during crises.
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