Lake Koroneia near Thessaloniki, once a key habitat for wildlife that included rare birds, has completely dried up and any effort to restore it to its former state is likely to be extremely difficult, scientists have said.

A lack of rainfall in recent months and high summer temperatures mean that only sludge has been left at the bottom of the lake, which had been the focus of repeated efforts to save it from disaster.

The latest effort to rescue the lake, which is set to receive 27 million euros in European Union funding, has stalled in the assessment and tender phases of the project.

The drought has led to thousands of birds, including pelicans, finding new habitats.

Scientists say that any efforts to divert water from rivers or nearby Lake Volvi would be an extremely complex undertaking that would have no guarantee of success.

“The sustainable restoration of Lake Koroneia is very difficult and will have to be approached from many scientific angles, while ensuring the protection of Lake Volvi which is also in an average ecological state and is in need of care,” said Maria Matsouka, a biology professor at the Aristotle University of Thessaloniki.

Following the death of some 30,000 birds at the lake in 2004, a plan to protect Koroneia was drawn up by authorities but has never been implemented. Some 200 birds were found dead at the lake, some 20 kilometers east of Thessaloniki, last September.

Koroneia had been described as Greece’s dirtiest body of water, believed to contain the highest rate of cyanobacteria (blue-green algae) in the world.