blue green algae

blue green algae

Improving water quality

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Zwanen in recreatieplas

De Gouden Ham

The recreational site, the Gouden Ham, lies in an old meander of the Maas river between Maasbommel and Appeltern. The meander was formerly used for sand extraction and, apart from a small inlet, is completely separated from the river. 

A large lake of about 220 hectares was created as a result of the excavation work that took place during the seventies. Today, the lake is as deep as 40 meters in places and is suitable for recreational use and wildlife. Over summer, the lake is used for boating and swimming and there are multiple camping sites, holiday homes, marinas, hotels and food & beverage services around the lake.

The wildlife is concentrated around the east of the area (Binnenmeer and Moringerwaard). Here, large groups of birds come to rest or forage.

Luchtfoto recreatiegebied De Gouden Ham

Recreational area the "Gouden Ham"

Blue green algae

Blue green algae are bacteria which live in surface water and, when present in large quantities, can look like seaweed. During warm weather, blue green algae can proliferate within a short period of time. The algae consume a lot of oxygen in the water, leaving little for aquatic fauna, like fish for example.

When present in large concentrations, they can produce toxins which can cause irritation and diseases and they are therefore undesirable in water where recreational users can be exposed to the toxins through swimming or playing.

The page Blue green algae contains more information about the conditions in which blue green algae may develop

Alg (400x vergroot)

Alga (400x enlarged)

Active approach

In cooperation with the province of Gelderland, Rijkswaterstaat Limburg and the management association of De Gouden Ham, the Recreation Corporation went searching for short and long term measures for blue green algae control. Different short term measures have been implemented to prevent or postpone the formation of scums. On the page Research we give an overview of these efforts.


The efforts undertaken to control blue green algae at Het Groene Eiland have brought the first results. Actions undertaken at the swimming lake within the camping ground Het Groene Eiland during 2008 have demonstrated that good results can be achieved by a well thought package of measures. The water quality in this enclosed bay has been perfect for the the whole season and recreational activities such as swimming and playing in the water have been possible throughout the season without any problem.

The pages Research and Conclusions provide an overview of the research and the lessons learnt are shown.

This is also only a interim result. We currently work on solutions for the whole recreation area of more than 300 hectares. Through this site we keep you up to date about research, measures and further results.
Helder, veilig water in zwembaai

Results: clean, safe water in swimming area

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Onderzoek mede mogelijk gemaakt door Euregio Rijn-Waal