Last Sunday, part of the water of the Grand Canal in Venice, Italy, turned a phosphorescent green, drawing the attention of tourists and the confusion of authorities.

The change in the color of the water was reported by residents, the president of the Veneto region, Luca Zaia, reported on Twitter.

Despite the discoloration of the water, the gondoliers continued their work.

“The prefect called an urgent meeting with the police to investigate the origin,” Zaia added.

In 1968, the Argentinian artist Nicolás García Uriburu colored the water of this street during the 34th Venice Biennale to create awareness about ecology.

Authorities took samples of the water to determine what substance had spilled and whether it was prompted by an outcry from environmentalists.

He local newspaper La Nuova Venezia interviewed Maurizio Vesco, from the Regional Environmental Protection Agency, who indicated that there are several theories about what happened in the canal. One is that it spreads fluorescein, a harmless environmental dye used to detect a particular water stream. It is mainly used by plumbers.

Already this Monday, the presence of the substance was confirmed through ecotoxicological analysis, as well as the exclusion of a hazard for water.

The person responsible for the incident is being sought, although it has not yet been ruled out that it could be due to an error in not immediately seeing a discoloration and pouring more than necessary. In addition, a plan is being worked on to prevent new episodes of this type.