Serbia's largest salt lake dries up amid relentless heatwave

It was the largest salt lake in Serbia, and its medicinal mud has been used in healthcare for hundreds of years. However, as a result of the heatwave that has lasted for many days, the "miraculous lake" has completely dried up.

The natural reservoir, from which the medicinal mud was famous throughout Europe, was Lake Rusanda. It covered an area of 1.5 square miles when it was filled with water. Near its shores, the Special Rehabilitation Hospital "Rusanda" was established, whose activities were mainly based on treatments using local mud.

Medicinal mud and Peloid (organic sediment from thousands of years ago) were extracted from the bottom of Rusanda since the mid-18th century. This was not difficult since the lake was always very shallow. Therapy with substances from this place successfully treats muscle inflammations, rheumatism, gout, and general contusions, such as for people after car accidents or falls from great heights.

The last few weeks have been very challenging for this place. The water in the reservoir dried up completely. On social media, many photos can be found showing how the former basin looks now. Dry, cracked ground, no sign of mud or living creatures.

- We are dealing with an extreme weather event: a heatwave characterized by exceptional length and intensity — said Vladimir Dziurdziević, a meteorologist from Belgrade, to the Reuters agency.

Both in Serbia and the entire Balkan Peninsula region, for over a week now, there have been extremely high temperatures of both air and water. Authorities are urging residents and tourists to be particularly cautious and to stay indoors as much as possible. In some countries, red weather alerts are in place, and many regions are struggling with fires.

Rusanda is located in northern Serbia, in the Autonomous Province of Vojvodina. Near the lake, in the village of Melenci, a spa was founded. The lake is divided into two parts: the larger Velika Rusanda and the smaller Mala Rusanda. They are separated by an asphalt road.

Due to the high salinity of water and mud, reaching 60% (typical for seas), there was a hypothesis that Rusanda is one of the remnants of the ancient Pannonian Sea, but after deeper examination, it turned out to be a so-called fossilised bed of the Tisza River.

Despite the concern among people using the natural benefits of this place, hydrologists are reassuring everyone who is worried about the state of the lake. According to specialists, the periodic drying of the reservoir during the hot summer period is not happening for the first time. A similar phenomenon occurred, for example, in 2017 or the early 20th century. If the drought lasts a few months, it does not disrupt the ecosystem of this unique basin, nor does it cause the permanent loss of the mud's medicinal properties.

When heavy rains start in the autumn, Rusanda will probably refill. Hydrologists have concluded that the periodic drying of the reservoir was caused by the construction of the Danube-Tisza-Danube canal system (in the 19th century), resulting in the disturbance of groundwater levels, which – despite many years – persists to this day.

Knowing about the potential for the lake to dry up, the employees of the Special Rehabilitation Hospital "Rusanda" always have a large stockpile of mud collected from the bottom when the basin is full. It turns out that the material extracted during the drought loses its medicinal properties and, after artificial soaking, is not suitable for use in rehabilitation.