Lake Zug and a number of other Swiss lakes are polluted with animal manure. The problem stems partly from Switzerland’s oversized livestock sector fed on imported feed.
Scientists can gauge of the scale of the problem by measuring the phosphorus content of lake water. In Lake Zug there is currently 80 milligrams of phosphorus per cubic metre of water, a level close to triple the federal guideline of 30 milligrams per litre.
In lakes, phosphorus promotes the growth of algae. When algae dies it sinks to the bottom where it is broken down by fungi and bacteria, a process that consumes much of the oxygen in the water. Oxygen depleted water then threatens fish and plant biodiversity in the lake.
In Zug there was a project to limit the negative impacts of farming on the lake. However, the farmers’ association abandoned the project. It seems the problem stems from the plan failing to fit with federal government plans and the expectations of farmers.
One element of the project involved adding sand filters to the end of existing farm drains. However, it was unclear how much funding would come from the federal government and farmers were not happy about making long term financial commitments to the project, according to a report by SRF.
WWF Zug voiced disappointment at the decision to abandon the project. The environmental organisation recommends eliminating inflow zones and creating zones in the lake catchment area where farmers would be required to cut livestock numbers.
Environmental organisations and local politicians with environmental agendas look set to continue applying pressure to local farmers to cut their pollution.
SRF article (in German)