Hungary’s Lake Balaton will no longer be the largest freshwater lake in Central Europe?

As we all know, Lake Balaton is Central Europe’s largest freshwater lake. However, the water of the Hungarian Sea is going through a significant change due to human intervention. Lake Balaton is getting saltier and saltier which is a danger to its wildlife.

VEOL asked an expert to answer questions surrounding the changes in Lake Balaton’s water composition. Lajos Vörös, a member of the Balaton Limnological Research Institute, talked about the lake’s future. He said:

Up until the middle of the last century, Lake Balaton was the largest freshwater lake in Central Europe, but that has changed. The water of Lake Balaton is no longer fresh water but is now also called “fresh-salty transitional water” in the local terminology.

According to the internationally accepted classification, the upper limit of total salinity in freshwater is 500 milligrams per litre. Lake Balaton was under this limit until the mid-twentieth century. Today, the salinity of the lake is around 700mg/litre.

Why is the water so soft and silky?

According to Lajos Vörös, the water of Lake Balaton is slightly alkaline, which makes it soft and silky. On the pH scale, water with a pH of 7 is neutral, however, the “Hungarian Sea” has a pH level of 8.5. The expert says:

The waters in our area and in our rocky shelf have three main mineral components: calcium, magnesium, and bicarbonate. Calcium and bicarbonate dissolve from limestone, and magnesium from dolomite. The waters flowing into the lake contain a lot of carbon dioxide.

As the water settles in the bed of Lake Balaton, the dissolved carbon dioxide slowly equilibrates with that in the air. Calcium carbonate (limestone) forms because of chemical reactions. Therefore, calcium might be the dominant element in the inflowing water, but magnesium is the dominant element in the water of Lake Balaton.

Human impact on the freshwater

The ecologist also said that the composition of the water has been researched since 1927. From this data, we can learn that humans had a shocking impact on the freshwater of Lake Balaton. The amount of table salt in the water has increased fivefold in the last half-century. The water of the Hungarian Sea is therefore becoming saltier, and in fifty years’ time, bathers will even feel this change. For now, the saltiness does not take away from the enjoyment value.

Table salt is used for de-icing the roads in winter, as well as coastal constructions. Thus, it easily ends up in the waters of Lake Balaton. In addition, potash fertiliser used in agriculture and treated household wastewater also end up in the lake. Due to the more intensive de-icing with salt in Northern countries, this phenomenon is also present elsewhere.

Will this affect the wildlife?

According to Lajos Vörös, wildlife is already struggling. Fortunately, nature can adapt so the lake’s wildlife will not be extinct. The expert also added:

There are living things in all kinds of water. Water purity is a human concept. The amount of algae in the water depends on the amount of phosphate and nitrate ions, of which a lot is desirable in a fishpond, but the same can be unpleasant, even exclusionary, in water used for bathing. Wastewater must be treated to prevent nitrogen and phosphorus from entering the lake so that the water is clearer and cleaner.

The Hungarian government has been actively fighting algae since the seventies and eighties. Due to the construction of a wastewater treatment network, the amount of phosphate coming to Lake Balaton is much lower.