Izmir, a Mediterranean port city with a history of 8,500 years, is situated on a landmass where rivers flow between perpendicular mountains and meet the sea, creating a network of water sources and a bay formed by river deltas. The presence of freshwater resources from the mountains has played a crucial role in sustaining human settlements in this area over the centuries. These unique geographical and ecological features have allowed Izmir to maintain its historical identity and biodiversity as an ancient city. The bay of Izmir has played a significant role in shaping the city and influencing global civilizations through international trade. It has been the lifeblood of the city, sustaining its vitality throughout history.
The biggest ongoing problem in Izmir for the past half-century has been the pollution of its bay. The detrimental effects of pollution, such as loss of biodiversity and unpleasant odors, have necessitated urgent action. In response, the Izmir Metropolitan Municipality has been proactively addressing this issue, taking decisive measures to combat pollution and preserve the environmental integrity of the bay.
The Blue Infrastructure Program works towards the conservation of aquatic ecosystems of Izmir, primarily the Izmir Bay and Gediz Delta, and their sustainable management in harmony with nature. As a key partner, IZPA assists Izmir Water and Sewerage Administration (IZSU) for the implementation of this program.
The Izmir Living Bay Strategy is based on the principle of surrounding and permanently eliminating the pollution flowing into the bay for the past 50 years through infrastructure and implementation projects from land, coast, and sea. With the 10 Living Bay projects conducted on land, along the coast, and at sea, which complement and support each other, the goal is not to cover up the pollution in the Izmir bay but to completely eliminate it. The Living Bay Strategy provides a permanent solution to one of Izmir's main problems through a 50-year plan.
Below, 10 key projects that collectively form the Living Bay Strategy are described in detail.
MEASURES ON LAND
The first stage of the 3-stage Living Bay Strategy is the projects conducted “on land”. With the completion of the city's rainwater separation infrastructure, rainwater will directly flow into the bay without being contaminated with sewage water. This will relieve the pressure on our wastewater treatment plants. Another important intervention to be carried out on land is the restoration of streams. By restoring the streams that flow into the Izmir Bay, the city of Izmir will reconnect with its streams, and the restored streams will filter the water flowing into the bay.
1. Rainwater Drainage Pipe System
The wastewater infrastructure of Izmir is largely based on a combined system, where rainwater and wastewater are collected in the same sewage line and directed to wastewater treatment facilities. Due to this combined system, both rainwater and wastewater are polluted, and the capacity of wastewater treatment plants is strained according to their load. With the completion of the city's rainwater separation infrastructure, rainwater will directly flow into the Bay without mixing with sewage and without becoming polluted. Over the last four years, 220 kilometers of rainwater separation lines have been completed, and the construction of a 270-kilometer rainwater separation line is planned for the upcoming years.
2. River Restoration Program (Meles, Balatçık, Bostanlı, Bornova, Peynircioğlu)
The inner Bay of Izmir consists of over 30 stream basins. Flowing from Yamanlar Mountain, Nif Mountain and Kızıldağlar Mountain to the Bay, these streams pass through urban and industrial areas. Many of these streams were concretized through projects in the past, and today they sometimes don't flow at all and other times due to heavy rainfall, they reach the Bay with high flows. With concrete floors and walls, these streams have lost their ecological character and their connection to the soil has been severed.
Concrete riverbeds where no plants grow discharge the heavily polluted water from urban and industrial areas directly into the Bay. The restoration of selected streams that flow into the Bay is of critical importance to restore the marine, coastal and aquatic habitats around the Gulf of Izmir. This program aims to eliminate pollution sources in the Bay, create ecological corridors and buffer zones within the city, and provide new green areas for the people of Izmir. Meles, Balatçık, Bostanlı, Bornova, Peynircioğlu streams are chosen as pilot areas under this program.
IMPROVEMENTS MADE ALONG THE COAST (TREATMENT FACILITIES)
The second phase of the strategy is the revision and capacity enhancement practices carried out at the wastewater treatment plants along the bay coast. By implementing capacity enhancement and revision projects with a future-oriented approach, the city aims to achieve adequate wastewater treatment capacity for the next fifty years. The revisions and capacity increases at the Çiğli Wastewater Treatment Plant and Narlıdere South-West Wastewater Treatment Plant will provide relief to both the bay and the city. The establishment of a new facility in Karabağlar will not only reduce the burden on other plants but also create a freshwater source for the Meles River by discharging treated wastewater into it, thereby establishing an ecological corridor within the city. This project also serves as a complement to Expo 2026, with a focus on the Meles River. The integration of a recovery unit at the Çiğli Wastewater Treatment Plant will allow the utilization of high-quality reclaimed water obtained from wastewater for agricultural and urban irrigation needs. With the renovation and capacity increase of the sludge digestion and drying facilities at the plant, the dried sludge will be transformed into a valuable fuel source for industries like cement, thereby making a significant economic contribution.
1. Rehabilitation of Phase. 1, 2 and 3 of Çiğli Wastewater Treatment Plant
The Çiğli Wastewater Treatment Plant, commissioned in the year 2000, is currently operating with a total capacity of 600,000 m³/day through a parallel structuring of 3 phases. With the increase in Izmir's population, the need has arisen to expand the facility's capacity and rehabilitate the existing phases. In this context, the revision and renewal work of the current 3 phases of the plant are being carried out. Upon completion of these works, the treatment efficiency of the facility will reach higher standards.
2. Construction of Phase 4
With the construction of Phase 4, the increase of an additional capacity of 200,000 m³/day will be added to the existing 600,000 m³/day capacity, bringing the total operational capacity of the plant to 800,000 m³/day. The construction of Phase four of Çiğli Wastewater Treatment Plant started in June 2023.
3. Water Reuse Project
Wastewater treatment plants hold significant potential for the reclamation of water used in domestic consumption. With the activation of Phase 4, the Çiğli Wastewater Treatment Plant will reach a daily wastewater processing capacity of 800,000 m³/day. Through the Wastewater Reclamation Project, the water treated to wastewater treatment plant standards will undergo further processing in the Reclamation Unit, and its quality will be elevated to a level suitable for use in agriculture, industry, and urban parks and gardens.
The reclaimed water will be transferred to adjacent agricultural areas. The water directed to the Menemen Plain will be used for agricultural irrigation complemented by nature-based crop planning. Additionally, a significant portion of the water will be directed to the Gediz Delta, to restore lagoons and other coastal habitats.
4. Construction of the Karabağlar Wastewater Treatment Plant
Planned to serve the entire districts of Gaziemir and Buca, as well as half of the district of Karabağlar, the Karabağlar Wastewater Treatment Plant is aimed at increasing the city's wastewater treatment capacity and reducing the load on the Çiğli Wastewater Treatment Plant by 15%. The facility, to be established at the İZSU Campus in Karabağlar, will be an advanced wastewater treatment plant using state-of-the-art technology, and like many modern cities, it will be constructed underground to provide its services. This plant, which will also contribute significantly to the cleanliness of the Bay, will accelerate slow sewage flow that occasionally leads to odors in inland areas. By directing the treated wastewater from this facility into the Meles River, a freshwater source will be created for the Meles River, enabling its restoration, and an ecological corridor to be established in the city center. With a budget of 850 million Turkish Liras, this project, set to be completed by 2026, will also serve as a complement to the Expo 2026 program.
5. Improvement of Narlıdere Southwest Wastewater Treatment Plant
The Southwest Wastewater Treatment Plant, purifies the wastewater from Narlıdere and its surroundings and discharges it into the Bay through deep discharge. For the facility, which has been serving the city for many years, a process of revision and capacity increase has been initiated. With a budget of 400 million Turkish Liras allocated, the revision and capacity increase efforts will enhance the wastewater infrastructure. Currently, the wastewater from Narlıdere's Altıevler and Huzur Neighborhoods, which goes to the Çiğli Wastewater Treatment Plant, will be redirected to the Southwest Wastewater Treatment Plant following the capacity increase. As part of this, the existing wastewater pipeline serving all of Narlıdere will be renewed, and approximately 9 kilometers of new pipeline will be constructed. This supplementary project will be realized at a cost of 105 million Turkish Liras.
6. Rehabilitation of the Mud Dehydration Complex
Two important outputs of the wastewater treatment plant process are treated sludge and water. The sludge generated from the treatment process can be processed through various methods and utilized as a raw material in sectors like agriculture and industry. By establishing a drying facility within the Çiğli Wastewater Treatment Plant, the sludge produced from the treatment process will be processed to achieve the required level of dryness and converted into a resource. The drying facility, powered by biogas generated from the sludge itself, will process the sludge on a daily basis, and the processed sludge will be utilized as a fuel raw material in the cement industry. The transformation of wastewater sludge, with its attractive high calorific value, from waste to raw material will also bring economic benefits.
IMPROVEMENTS MADE AT THE SEA
The third and final phase of the Living Bay of Izmir Strategy includes projects to be carried out in the bay itself. The pollution problem, which is surrounded and mitigated from both land and coast, will be completely eliminated through projects conducted at sea, also supporting the restoration of the aquatic ecosystems. Currently, the treated wastewater from the Çiğli Wastewater Treatment Plant is discharged into the inner bay through a canal. With the Diversion Channel Project, we will transport the treated freshwater through a natural stream-like diversion channel first to the Old Gediz riverbed and then to the central bay. By moving the existing discharge point four km westward, we will restore the natural ecosystems in the Southern Gediz Delta.
Another project carried out at sea is the Restoration Project of Çilazmak Lagoon. The clayey, organic sludge obtained through the seabed scanning carried out at the discharge point of the Çiğli Wastewater Treatment Plant will be utilized in the coastal reinforcement and restoration of the Çilazmak Lagoon. This project will not only support the biological diversity of the Bay and the Delta of Gediz but also contribute to the city's economy by enhancing seafood and fish stocks in the bay.
1. Derivation Chanel
The South of the Gediz Delta is coming back to life through the Çiğli Wastewater Treatment Plant. With the ongoing revision works at the facility and the implementation of Phase 4, the treated water released from the plant reaches a quality suitable for ecological restoration, returning to the source of life.
In the mid-19th century, the bed of the Gediz River, which flowed from Çiğli to the Bay, was shifted to the Foça side. The interruption of freshwater input led to significant and adverse transformations in the ecosystem of the region known as South Gediz, where the old riverbed was located, subjecting the area to salinity pressure.
The Diversion Channel project involves creating meanders between the Çiğli Wastewater Treatment Plant and the old bed of the Gediz River. A natural riverbed will be opened, and the treated water will be directed to the old bed of the Gediz River through this channel. Flood-prone areas will also be established along the diversion channel allowing fresh water to enter the region under salinity pressure. The introduction of freshwater will break the salinity pressure, and the area will regain its ecological balance. The project will increase the biodiversity of the South Gediz, positively impacting the biological diversity of the area. Additionally, animal husbandry activities will be carried out and supported in the created flood-prone areas.
2. Restoration of the Çilazmak Lagoon
The northern coast of the Izmir Bay, enriched over thousands of years by the alluvium carried by the Gediz River but also experiencing shallowing, contributes to sediment accumulation within the Bay due to limited water circulation. The area, where the discharge outlet of the Çiğli Wastewater Treatment Plant is also located, faces significant shallowing and sediment accumulation issues, leading to restricted water circulation. Seafloor scanning activities are carried out in this region, and the collected sediment was previously deposited in an area determined by the Turkish Ministry of Environment and Urbanization and Climate in the vicinity of Foça.
With the implementation of the project, not only will shallowing and sediment accumulation be prevented, and water circulation strengthened, but also the Çilazmak Lagoon, which has been on the brink of disappearing for decades, will be restored and revitalized. Sediment scanned from shallow areas will be transferred using pumps and utilized for coastal reinforcement in Çilazmak Lagoon. The sediment, free from any sources of heavy metal or pollution, will transform into an important area for biological diversity along the dune coastal cord.
By restoring Çilazmak Lagoon to the Izmir Bay, biological diversity in the Bay will be supported, providing a new breeding and feeding ground, especially for fish. The increase in marine life and a healthy lagoon structure will create a habitat for shore-birds and sea-birds. Through this project, traditional coastal fishing, an important cultural tradition of the region, which was on the verge of disappearing in the Izmir Bay, will be reinforced and contribute to the local economy.