Level of water in lake almost at its lowest since records began

The level of the water in Lake Zug is currently almost at its lowest since records began in 1930.

What with ongoing warm weather, lack of rain and brown patches evident in the fields, it is not surprising that the level of water in Lake Zug is very low. As of 2 pm last Thursday, 19 July, it was at 413.23 metres above sea level, in other words some 37 centimetres lower than the long-term summer average. The absolute lowest level, 413.12 metres, was recorded over 70 years ago in October of 1947.

The situation is similar in Lake Aegeri, too, where at 2 pm on 19 July, when a level of just 732.34 metres above sea level was recorded, the lowest ever level being 723.23 metres in November of 2015.

Naturally the level of the lakes affects the shipping services, too, not least with regard the additional difference in height between the ships and embarkation and disembarkation gangways, as Karin Fröhlich of the ZVB explained. “So far we have been able to maintain all our services and stops, but we are keeping a close watch on the situation,” she said.

Reassuringly, Roland Krummenacher, who heads the Department of Environmental Protection, said that the level of water on Zug’s lakes was not yet critical with regard to supplies of drinking water and energy, with water able to be taken from the lakes with no dire consequences. However, this was not the case with regard to taking water from the River Reuss, where removing even some water could have an adverse effect on fish there, with water taken from smaller rivers and streams “practically out of the question” at present.

Not unexpectedly, increasing temperatures of water in rivers and streams has a deleterious effect on fish such as trout, temperatures of 19°C and above causing levels of stress, and death if temperatures rise above 25°C. At present, in the canton of Zug, there is no need for fish to be removed from the rivers to help them survive, unlike in the canton of Lucerne.

“Fortunately, there are sufficient levels of groundwater,” too, added Krummenacher, “so the situation is not critical here, either.”

Trees are also suffering from the lack of rain. “This is particularly the case in areas where they are exposed to the south,” said Raphaela Tinner of the Office of Care and Protection of Woodland. “Some trees are showing evidence of stress and indicating symptoms of not getting enough water, for example in closing the pores on their leaves. If they did not do this, they would just dry out,” she explained, all of which could lead to them showing signs of an early autumn and discarding their leaves early, a situation which could also lead them to being more susceptible to bark-beetle and fungal attack.

What is needed to remedy this situation is a sustained period of rain. While thunderstorms are often accompanied by heavy falls of rain, the ground cannot take it all in. “What is needed is a lengthy period of wet weather, to moisten the ground in a sustainable way,” added Tinner. “This would also reduce the risk of forest fires.”

Not unsurprisingly, farmers are suffering, too, as grass is not growing, as Thomas Rickenbacher, the president of the Zug Farmers’ Association, explained. “If hay put aside for winter feeding is having to be used now, then more will have to be bought in or the size of herds reduced,” he warned. On the positive side, he mentioned that this long period of drought had led to fewer cases of fungal attack on fruit, meaning a good year for berries.