Trichonis Lake is the largest natural lake in Greece, covering approximately 97 km², with a maximum length of 21.5 km and a maximum depth of 58 m. Its surface elevation is approximately 15 m above sea level, while water temperatures fluctuate seasonally between 4°C and 25°C. The lake represents a biodiversity hotspot of exceptional ecological importance, supporting a wide variety of endemic and native species, including algae, fish and avifauna. Due to its high ecological significance, Trichonis Lake and its surrounding wetlands are protected under several international conservation frameworks, including the NATURA 2000 network (site code GR23100090), the EU Habitats Directive 92/43/EEC, and the Ramsar Convention on Wetlands of International Importance.

In addition to its ecological importance, Trichonis Lake provides a range of ecosystem services that are fundamental to the regional economy and human well-being. These include the provision of irrigation water for agricultural production, support for commercial fisheries, and the promotion of religious tourism associated with historic monasteries located within its catchment. The lake therefore represents a natural resource of significant environmental, cultural and socio-economic value.

Despite the adverse impacts of anthropogenic activities, which have modified and degraded parts of the shoreline and contributed to the deterioration of littoral habitats and associated ecosystem functions, Trichonis Lake has retained a high degree of ecological integrity. Its favourable geological and hydrological characteristics have contributed to comparatively good water quality relative to many Mediterranean freshwater ecosystems. These conditions provide important opportunities for biodiversity conservation and the implementation of sustainable lake management strategies.

Building on the extensive scientific knowledge accumulated through limnological studies, technical reports and stakeholder engagement over recent decades, the ProCleanLakes project will develop and implement both conventional management measures and innovative Nature-based Solutions (NbS) to mitigate diffuse and point-source pollution and enhance ecosystem resilience. The interventions will be informed by a comprehensive environmental baseline and adapted to the specific ecological and socio-economic characteristics of the Trichonis Lake watershed.

Alongside conventional management actions, including the long-term monitoring of biological communities and water quality, the project will investigate an innovative NbS based on the cultivation of selected native microalgal species in raceway pond systems. This approach has the potential to simultaneously remove excess nutrients and other agricultural pollutants, including olive mill wastewater, while generating high-value biotechnological products such as biomass, pigments and bioactive compounds. By integrating environmental remediation with resource recovery, the approach aims to deliver multiple ecological and socio-economic benefits and contribute to the transition towards a sustainable circular bio-economy.