The Swiss Federal Department of Defence Procurement (Armasuisse) is offering 50,000 Swiss francs ($57,800) for the three best ideas on how to retrieve some 12,000 tonnes of old munitions from the country’s lakes, including Lake Thun, Lake Brienz and Lake Lucerne.

“Armasuisse wants to involve academia and industry in the considerations on how environmentally friendly and safe recovery of deep lake ammunition could be carried out,” according to a department statement.

It is thought the operation to remove the munitions, which were dumped between 1918 and 1964 could cost the government billions of francs.

So why do Swiss lakes contain old munitions and why is Switzerland so eager to retrieve them now?

Why are there munitions in lakes in Switzerland?

Some 12,000 tonnes of munitions were dumped by the Swiss military into Swiss lakes over the course of many decades following the first world war. Due to Switzerland’s limited space and high-density populated areas, it was considered a “safe” way to dispose of both excess and faulty ammunition stocks.

In some lakes, these munitions have sunk to depths of between 150 to 220 metres (492 – 721 feet). In others, however, such as in Lake Neuchatel, munitions are just six or seven metres (20 – 23 feet) below the surface.

Was lake-dumping a common way to dispose of munitions?

Switzerland is by no means the only country to have disposed of munitions in this way.

According to a 2017 report from the John Martin Center for Non-Proliferation Studies, which campaigns against weapons of mass destruction (WMD), roughly 1.6 million tonnes of munitions have been dumped in many of our major lakes, seas and oceans, between 1918 and 1970, with high munition dumps concentrated in seas close to Germany and the United Kingdom.

Experts believed the deep waters of lakes and seas would effectively “isolate” the munitions, preventing them from causing harm. The assumption was that the underwater environment would contain any potential chemical hazards while leaving munitions undisturbed, lowering the risk of an explosion.

Why does Switzerland want to retrieve these munitions now?

In recent years, concerns have mounted that the dumped munitions could be causing environmental damage.

Retired Swiss geologist Marcos Buser wrote a report 10 years ago stating that munitions could be contaminating the water and soil around the lakes with trinitrotoluene (TNT), a chemical compound used in explosive munitions.

Then, in a 2020, a collaborative report published by the Polish Academy of Sciences, the Institute Helmholtz Centre for Polar and Marine Research (Germany), and the Marine Research Centre (Finland), also found a risk of seawater contamination from the munitions.

The report stated, “Such munitions are a threat for maritime workers, but also for the environment. Corroding shells release toxic degradation products to sediments and bottom water and, unlike other contaminants, they cannot be reduced by land measures. Only removal of the source can reduce the contamination.”

It is also understood that the fuses within many of the munitions were never removed before they were dumped, meaning there is still a risk that they could explode. Thankfully, none of the dumped munitions have exploded so far.

Why has a competition been launched to find a solution?

In short, the Swiss authorities have run out of ideas, having faced a litany of obstacles in their attempts to solve the problem up until now.

Experts who carried out an assessment of the risks posed by the dumped munitions in 2005 concluded, “All proposed solutions for ammunition recovery available at the time would lead to massive sludge turbulence and high risks for the sensitive ecosystem of the lake.”

Poor visibility below the surface of the water in Switzerland’s lakes, plus the risk of explosions, have further hampered progress.

According to Armasuisse, some munitions components are made of non-magnetic copper, brass or aluminium, making it hard to detect their locations.

Armasuisse continued, saying, “It is not planned to implement the submitted entries immediately, but they could serve as the basis for further clarifications or for launching research projects.”

The deadline for submissions has been set for February 2025. The announcement of the winner, or winners, will take place in April.