This special natural phenomenon also took place five years ago. At the time, administrator of Natuurmonumenten thought that the discoloration was probably caused by persistent drought on the island in combination with micro-algae. At the time, Natuurmonumenten and the Royal Netherlands Institute for Sea Research (NIOZ) were investigating the phenomenon.
It is unknown whether the water is still safe for humans and animals. There is currently bird flu on Texel, including in Wagejot, where dozens of terns have since died.