Huge quantities of discarded ammunition have been discovered in Norway's largest lake.
While it was no secret that ammunition crates and other gear were dumped into Lake Mjosa between 1940 and 1970 by both the Raufoss factory and the Norwegian Armed Forces, a recent calculation by the Norwegian Defense Research Institute (FFI) indicated that the extent of the unused and defective ammunition tossed into the waters was much greater than previously presumed.
In the past, it was believed that between 100 and 200 tons were dumped in total. A new estimate said that this figure could be 10 to 20 times higher.
"We have sources that say that 30 tons could be dumped in a single day. This traffic went on for many years. Our findings support the fact that the quantity is far above what has been said," chief FFI researcher Arnt Johnsen said in a press release.
The junked weapons involve everything from thousands of three-meter-long Sidewinder air-to-air missiles to crates with grenades and historic arms from World War II. Much of the ammunition is undetonated and can therefore be hazardous. After lying in the lake for close to 80 years, ignition mechanisms can become unstable and can explode if touched.
So far, however, no concrete documentation on the exact types of ammo, quantities and dumping sites has been found, according to FFI. The Norwegian military was asked by the Norwegian Environment Agency to survey the distribution of ammunition previously chucked into Lake Mjosa. A full report is due this autumn.
The discarded weapons may also pose a health hazard. In measurements from late 2020, traces of two types of dinitrotoluene (DNT) at the bottom of Lake Mjosa were uncovered. So far, no discoveries were made in the water directly above. DNT is a common substance in explosives, which is both toxic and carcinogenic. Furthermore, the ammunition at the bottom of the lake may contain environmentally harmful mercury, lead and copper.
A total of five municipalities with a population of 100,000 people get their drinking water from Lake Mjosa. In the future, the leak of these substances into fresh water may intensify due to corrosion.
Mjosa is not only Norway's largest lake, but one of Europe's deepest, with a maximum depth of around 450 meters. It is located in the southern part of the Nordic country, about 100 kilometers north of Oslo. Previously, Lake Mjosa has been described as a treasure trove for old ships, as huge battles were held there in the 1100s and 1200s between large fleets.