Gyömrő Fishing Lake


The lake is situated inside the city of Gyömrő, and struggling with a very high sludge production / year due to the multiplication and death of the high number autotrophic species. The nutrien load is very high, mostly from municipal source. The lake is very shallow, which means that despite the eutrophic conditions, it has survived fish kills due to lack of DO in the past years.

The fisher’s association responsible for lake management asked us to start the remediation of the lake in June 2007. The main focus this year was on algae, and aquatic weed control, decrease the yearly sludge production, and establishing oxidative conditions in the bottom zone for stopping gas production from the sludge. The microbes started to decrease the existing sludge layer as well by digesting its organic content. The lake has had no algae blooming in 2007. The improvement of water quality is shown in table below.

Gyömrő Fishing Lake 21st June 2007. 1st October 2007.
Ammonium mg/l 0,64 0,48
Free Ammonia mg/l 0,0005
Nitrite mg/l 0,13 0,09
Nitrate mg/l 10,5 8,52
Ortophosphate mg/l 0,29 0,21
Total Algae Count / ml 39 402 21 220

A significant part of the microorganisms has settled to the bottom of the lake, and started the biodegradation of the organic sludge layer. The decrease of the thickness of the sludge was significant, as it is shown in the table below:

Date Height of sludge layer
2007. június 30 cm
2008. március 14 cm