Bärensee, Hanau, Germany 

An artificial, shallow, polymictic lake treated within Phoslock since 2007.

The Bärensee is located within the largest camping area in the Federal German State of Hessen and is a popular, highly frequented lake for swimming and fishing. The lake is surrounded on three sides by camping grounds, it has sandy beaches and is bordered by a mixed forest to the east. 

Eutrophication issues started in the 1990s, transforming the lake to a hyper-eutrophic state by 2004. Decline in water quality necessitated periodic swimming bans and severely decreased the recreational value of the lake. 

The lake was first treated with Phoslock (sold as Bentophos in Germany) in 2007. As the lake receives on-going inputs of phosphorus from swimmers using the lake and run-off from the surrounding campsite, smaller re-treatments were undertaken in 2010, 2013 and 2016 to maintain low phosphorus concentrations see from the first initial application.