Due to the recent dry and warm weather, the quality of the water in the Netherlands has been declining. The Rijkswaterstaat and water boards advise those looking to take a refreshing dip to do so only in official locations where the water quality is sufficient, so not in the canals, for example.
In the past week, there have been an increasing number of reports of blue-green algae (some types of which are poisonous), botulism, fish mortality and undesirable bacteria in the water. In the coming week, the temperature of the water is expected to increase and, as a result, the quality of the water will decline further.
If you are going out for a swim, it is best to check Zwemwater.nl first. The website is in Dutch, but gives some clear water quality labels: recente controle: in orde (recently tested: fine), nader onderzoek (undergoing further investigation) waarschuwing (warning) and zwemverbod / negatief zwemadvies (swimming ban / negative swimming advice). You can use the interactive map to find official swimming spots nearby and check the water quality.
The dry and warm weather in the Netherlands is not only responsible for the increase in bacteria in the water, but also the water level in canals and rivers. Due to the current drought, a code yellow has been issued for the river IJssel and the Rhine. The discharge of these rivers is currently low for this time of year.
By taking the necessary actions, The Rijkswaterstaat and water boards can still meet the water demand; however, they are keeping a close eye on the situation. Because of the low water level, ships have limited draught on various routes. The water level is also low in the Meuse; however, there is enough water in it to meet demand.