Following heavy rain in the past two weeks, the water level in the lakes of Neuchâtel, Biel/Bienne and Murten at the foot of the Jura mountains is “higher than average” and the ground is “saturated”, the federal environment office (BAFU) said in a statement on Wednesday.
In addition, the current milder temperatures will increase snow melt in the Jura in the coming days, it said.
From Saturday until the middle of next week up to 110mm of precipitation is expected in the Jura, Fribourg alps and Bernese Oberland, exacerbating the situation.
To prevent flooding, BAFU has approved a request by the canton of Bern to lower the water level in the three connected lakes.
To do so, water flow through the Port dam at the northeastern end of Lake Biel/Bienne will be increased “in a controlled and progressive manner”, essentially pulling the plug on the lake.
As a result, the river Aare, which flows in and out of Lake Biel/Bienne, will be running faster in the coming days, said the statement.
“This measure will increase the lakes' capacity for absorbing the forecast rainfall,” it said.
According to Meteo Suisse thunderstorms and rain are forecast for Switzerland from Saturday for the next few days.