The report, titled "OECD Environmental Performance Reviews: Turkey," notes that the Marmara Sea's Çanakkale and İstanbul channels are of particular importance to migrating fish but that the water quality is threatened in these areas, particularly from the discharge of untreated or lightly treated municipal and industrial wastewater.
The rising pollution levels of the Marmara Sea also threaten native crab species and the Mediterranean seal, as their natural habitats are being destroyed, the report notes. "A large segment of industrial wastewater and substantial amounts of municipal wastewater are mixing with seawater without being treated first. … Despite some progress, still approximately 53 percent of total industrial wastewater is discharged into rivers and coastal waters without any treatment, often containing mercury, lead, chromium and zinc," the report reads.
The report pinpoints İzmit Bay and Gemlik Bay as critical areas in Turkey that need immediate improvement on pollution control. In these areas, the Bosporus is a key source of waste matter, and increased ferry traffic on the Marmara is contributing even more pollutants.
The OECD also makes recommendations in the report, saying in particular that Turkey must promote industry's compliance with wastewater legislation by enforcing permit regulations and consequences for noncompliance.
"Despite efforts over the last 10 years, water quality has continued to drop, and flocculation levels have increased. … Under these conditions, public health and tourism potential in coastal water regions are threatened. … Many factors demonstrate that in the short term, larger investments are needed in pollution control," the report notes.