Methane Emissions from a Temperate Reservoir

A new study appeared in the scientific journal Environmental Science and Technology that has documented significant methane emissions from a temperate hydropower reservoir in Switzerland.  The field and modeling study found that the 90-year-old Wohlen See reservoir in central Switzerland is a very significant source of methane, almost entirely due to bubbling sediments. The total methane emission from Lake Wohlen was on average > 150 mg methane m²/day, the highest ever documented for a midlatitude reservoir.

The authors suggest that the specific characteristics of this reservoir – a flow-through reservoir with a short residence time and minimal oxidation, in addition to its high organic carbon load and fast sedimentation rate all lead to a high rate of methanogenesis. This leads the investigators to suspect that other similar run-of-river reservoirs lying downstream of large organic carbon sources may also be large methane producers.  

It is clear that more research is needed to be able to better quantify the methane emissions from temperate reservoirs globally. It's becoming clearer that dams are not a solution to a warming world, and in fact contribute to it.