Les Království reservoir faces extreme cyanobacteria bloom

The Les Království reservoir in the Czech Republic is experiencing an extreme cyanobacteria bloom, resulting in severe water quality degradation. Laboratory analyses have recorded chlorophyll levels at a record 1,767 micrograms per liter, which is more than thirty times higher than the threshold (30 to 50 micrograms per liter) that classifies water as unsuitable for swimming.

The reservoir's surface is covered with decaying biomass, foam, and grey patches, accompanied by unpleasant odors. Water transparency has dropped to between 0 and 50 centimeters. High water temperatures, reaching over 25 °C during August, and high concentrations of ammonia, phosphorus, and organic matter have contributed to the situation.

Povodí Labe, the reservoir manager, confirmed they are monitoring the situation closely but stated that manual removal of the biological material is not being considered as it would have no significant effect.