Why our waters have started to bloom

Sweden is experiencing a growing summer problem with algal blooms affecting its lakes and seas, turning waters into a murky, green soup and posing a threat to the environment. This phenomenon, which occurs during warm weather, is becoming a recurring issue, impacting both natural water bodies and ornamental ponds.

Globally, the problem has drawn attention, exemplified by a recent bloom in the reflecting pool at The Mall in Washington D.C. The U.S. president reportedly invested significant funds to restore the pool's clear blue appearance. Despite initial speculation about sabotage, the primary culprit was identified as a single-celled green alga from the genus Scenedesmus, common in many Swedish lakes but not typically found in such massive concentrations.

The article suggests that the conditions favoring these blooms are often related to nutrient-rich water sources, such as the Potomac River feeding the D.C. reflecting pool. Furthermore, factors like a dark-colored pond bottom, designed to absorb heat, can further accelerate algal growth. In the case of the D.C. pool, hydrogen peroxide was reportedly used in an attempt to kill the algae, though this may have contributed to the paint flaking off the pond's bottom.