Yuvacık Dam, which reached a critical level last year, was filled with recent rains.

The dam, located at the foothills of the Samanlı Mountains, was filled again with the rains that took effect in the autumn, following the decrease in water level due to the decrease in precipitation and increase in temperatures in the summer months.

According to the information compiled from Kocaeli Water and Sewerage Administration (ISU) data, 42 million 770 thousand cubic meters of water were stored in the Yuvacık Dam in Başiskele district as of November 9. The dam, whose occupancy reached 84 percent, reached its highest level according to measurements between 2016 and 2026.

According to data from the same period of the last 10 years, the occupancy of the dam is 25 percent in 2016, 32 percent in 2017, 26 percent in 2018, 33 percent in 2019, 25 percent in 2020, 42 percent in 2021, 23 percent in 2022, 33 percent in 2023. 20 percent measured in 2024. Last year, while there was 5 million 700 thousand cubic meters of water in the dam, the occupancy rate was recorded at 11 percent, which is considered a critical level.

The 84 percent occupancy rate of the dam reached double the 42 percent in 2021, which was the highest rate in the same period of the previous 10 years.

This situation revealed the importance of autumn rains in terms of the city's water resources.

The dam's annual purified water supply capacity is 142 million cubic meters.

Yuvacık Dam plays an important role in Kocaeli's water management, not only with the amount of water it stores, but also with its large water collection basin and natural nutrition resources.

The dam built on Kirazdere, which was formed by the merger of Hotdere and Soğukdere, originating from the Samanlı Mountains, is also fed by water from Kazandere and Serindere. The useful water volume of the dam, which has a 258 square kilometer water collection basin covering Kocaeli, Sakarya and a part of Bursa, is stated as 51.1 million cubic meters.

The precipitation falling into the basin is collected in the dam lake through stream branches, thus renewing the water reserves.

The raw water collected in the dam is delivered to Kocaeli through the network after being purified in the Kullar Drinking Water Treatment Plant. According to Metropolitan Municipality data, Yuvacık Dam meets approximately 80 percent of the city's water needs. The dam's annual purified water supply capacity is 142 million cubic meters.

Excess water can be transferred to Sapanca Lake

The role of Yuvacık Dam in the city's drinking water needs gains a regional dimension with the water transmission system established with Sapanca Lake.

In case the reserves in the Yuvacık Dam are insufficient during drought periods, the water taken from Sapanca Lake is delivered to the Kullar Drinking Water Treatment Plant via a special transmission line. Thus, Sapanca Lake is among the alternative drinking water sources of Kocaeli.

The other aspect of the water management system is the transfer of excess water to Sapanca Lake during periods when the water level in the dam rises. Once the Yuvacık Dam reaches full capacity, the sluice water can be sent to the lake thanks to the technical arrangement made at the Sapanca Pumping Center and the existing pumping station and the pipeline being operated in the reverse direction.

As the water released from the dam started to be transferred to Sapanca Lake in March, the water from Balaban Creek and some stream branches feeding the dam are also transferred to Sapanca Lake.

Thus, the water brought from Sapanca Lake to Kocaeli during dry periods can be returned to the lake when rainfall increases and the dam is filled. This connection between the two water resources allows the water reserves in the region to be utilized together.

Storing the precipitation that falls in the basin in the autumn and winter months in the dam not only increases the existing water reserves, but also supports meeting the water needs of the city in the summer months when the precipitation decreases.