Lake Iznik turned turquoise

Lake Iznik turned turquoise

Lake Iznik, the 5th largest lake in Turkey and the largest lake in the Marmara Region, has turned turquoise due to an algae bloom. Experts state that cyanobacteria, which feed on photosynthesis, come to the surface due to the lack of sufficient oxygen at the bottom of the lake.

In Lake Iznik, one of Bursa’s largest freshwater sources and surrounded by many agricultural lands, an algal bloom called “cyanobacteria bloom” occurred.

Lake Iznik

A layer of cyanobacteria, known as blue-green algae, covered the lake surface.
As a result of the decrease in the water level due to the temperature, the uncontrolled use of fertilizers in agricultural lands and the increase in the rate of phosphorus and nitrogen due to wastes, the algae layer at the bottom of the lake rose to the water surface.

Stating that the cyanobacteria fed by photosynthesis came to the surface due to the lack of sufficient oxygen at the bottom of the lake, Prof. Dr. Taner Yonar, a faculty member at Bursa Uludağ University (BUU) Faculty of Engineering, Department of Environmental Engineering, said that this situation poses a risk for other living things in the lake.


“Prof. Dr. Yonar said, “Eutrophication is a natural process. The concept of algal bloom we are talking about is a problem caused by the excessive input of carbon, nitrogen and phosphorus, which we call excessive amounts of nutrients, especially due to human sources, when the living conditions of these creatures are good, when the temperature of the sun is good, they dominate and grow excessively compared to other living things.”

Lake Iznik

Stating that we first feel this situation visually, Yonar said that the algal bloom can also occur in the seas and said, “We have red algae there. We encounter it frequently, especially in Izmit Bay. The concept of eutrophication is the general problem of stagnant waters. Especially if there is an inflow of pollution; this happens very quickly here and we need to talk about the reasons for this. Human resources are the main factor here.”


Stating that wetlands such as Manyas, Iznik and Uluabat lakes should be protected, Prof. Dr. Yonar said, “Iznik region is a valuable agricultural region and there is a pollution load coming from agricultural sources.”

Lake Iznik

“For example, there can be a serious use of fertilizers in agriculture here. We have two important big districts here. Orhangazi and Iznik. These have villages and residential areas. Although local administrations here take the necessary measures, treatment facilities do not reduce to zero.” Yonar continued as follows:

Lake Iznik

“They discharge with a certain discharge limit. If we talk about the concept of zero discharge, we will have these problems. Because these wetlands are a general problem of the world. A statement came from the highest authority of the Republic of Turkey. Our President said that Turkey is water poor. These areas are our potential water resources; Lake Manyas, Lake Iznik, Lake Uluabat. We need to protect these areas. We need to talk about concepts such as gray-black water separation for domestic water, their reuse, zero waste water for industry, and reuse of water returned from irrigation for agriculture. It is essential that we protect these resources. If we don’t, everything will collapse. The Chamber of Environmental Engineers in Bursa published a report. Agriculture uses 72 percent of it. In short, if there is no water, we are hungry.”


Gül Demirci

Hi, I'm Gul. I am a writer for Expat Guide Turkey and I strive to create the best content for you. To contact me, you can send an e-mail to Happy reading!

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