Seasonal Changes in Sewage Lagoon Colour

Public Service Announcement

Seasonal Changes in Sewage Lagoon Colour

October 15, 2026 – Iqaluit, Nunavut

 

The City of Iqaluit would like to inform residents that the green colour currently visible at the City's sewage lagoon is consistent with natural biological processes and seasonal changes as temperatures drop. 

 

The green colour is commonly caused by naturally occurring algae, which can play an important role in treating wastewater. 

 

As temperatures cool in the fall, the water in the lagoon naturally mixes in a process called fall overturn. This brings algae and other materials from different depths toward the surface, which can change the appearance and colour of the water. 

As ice begins to form, further natural changes occur in how the lagoon operates during the winter months. 

 

These seasonal processes are well documented in Canadian wastewater research and are normal for sewage lagoons in northern climates. 

The City wishes to reassure residents that green colouring alone is not a sign of a problem with the sewage lagoon. The City continues to monitor lagoon and waste water conditions as part of its regular daily operations.### 

For additional information, please contact: Dominik Gagne 

A/Communications and Customer Service Manager 

City of Iqaluit 

867-979-5607 | D.Gagne@iqaluit.ca