LIBRARY: Introducing the TETHYS4ADRION Pilot Rivers: The Alfeios River
The Alfeios River is one of the five pilot rivers being monitored as part of the TETHYS4ADRION project.
Stretching approximately 127 kilometers, it is the longest river on the Peloponnese peninsula in Greece. Its source lies in Mount Taygetos, located in the Arcadia region, and it flows into the Ionian Sea at the Gulf of Kyparissia, near the town of Pyrgos. Notable tributaries include the Ladon and Erymanthos rivers. Major settlements along the Alfeios include Megalopolis (a lignite-mining area), Olympia (a hub for culture and tourism), and Pyrgos (the commercial center of Ilia Prefecture).
The Alfeios River is a critical water source for irrigation, supporting local agriculture dominated by cultivation of olives, orchards, cotton fields, and vegetable crops. It also supplies water to the Megalopolis Thermal Power Plant and supports hydroelectric power generation, while several industries—such as olive mills, small agri-food processors, and wine producers—rely heavily on its resources.
The Alfeios ecosystem encompasses a wide range of habitats: from coniferous highland forests and dense pine and fir stands near its sources, to deciduous oak forests and herbaceous vegetation in the lowland plains.
The river’s delta and surrounding coastal lagoons (e.g., Kaiafas, near the town of Zacharo) are ecologically important wetlands that serve as vital habitats for migratory birds and endemic species. The river and its tributaries support unique fish species, such as the endangered Alburnus vistonicus and the protected European barbel (Luciobarbus graecus). Near its coastal outlet at Kato Samiko, the Alfeios River also features salt marshes, reed beds, and lagoons that support halophyte species (e.g., Artemia) and serve as nesting grounds for loggerhead sea turtles (Caretta caretta). The delta is a key stopover for bird species such as the grey heron (Ardea cinerea), mute swan (Cygnus olor), and mallard (Anas platyrhynchos). Among reptiles, the Greek terrapin (Mauremys rivulata) is also present.
One of the most severely polluted locations along the Alfeios is the Potoki site near Pyrgos, where an estimated 100,000 bales of compressed waste have remained along the riverbanks for nearly a decade. Further downstream, large quantities of waste are found in the Alfeios Delta (Kyparissia Gulf), while the lagoon of Kaiafas accumulates significant amounts of agricultural and plastic waste within its natural riparian vegetation.
Illegal dumping of construction, demolition, and renovation waste, along with unmanaged municipal solid waste, are major contributors to pollution. Tourism and recreational activities also play a role.
Plastic waste dispersal is further exacerbated by dams and weirs, flood events, and scattered small settlements. Numerous villages and hamlets lie along the river, many of which lack adequate waste management infrastructure. During rainfall, mismanaged waste is often washed directly into the river.
As a result of plastic litter accumulation, fish and other aquatic species may ingest microplastics, which can block their digestive tracts. At the same time, aquatic animals and birds are at risk of entanglement in plastic strips and nets. The presence of litter in key habitats can disrupt bird migration and interfere with sea turtle nesting.
Greek mythology tells us an interesting story about the Alfeios River. The river god Alfeios fell in love with the nymph Arethusa, who wanted nothing to do with him. To escape his pursuit, Arethusa fled to the island of Ortygia in Sicily, where the goddess Artemis turned her into a spring. But Alfeios was so determined that he flowed beneath the sea, all the way from the Peloponnese to Sicily, to merge his waters with hers.
This has been produced with the financial assistance of the European Union. The content of the website is the sole responsibility of TETHYS4ADRION project and
can under no circumstances be regarded as reflecting the position of the European Union and/or IPA ADRION programme authorities.