Series of 16 fishponds was monitored as a part of a drainage basin of Hracholusky reservoir, which is subject of a recovery project. All the fishponds were eutrophic – hypertrophic due to wastewaters from villages and little cities (including overflows from sewers) and/or due to too intensive production of “hunters ducks” – the phenomenon that is rarely mentioned.
High eutrophication is the main factor that has recently disabled the Jordán water reservoir for water supply and recreational purposes. Large-scale dredging of sediments was done between years 2011 and 2014. Thereafter a complex monitoring of water quality has been initiated since 2015.