Blue-green algae (Cyanobacteria) are photosynthetic bacterial organisms, naturally found in many types of water systems including lakes, rivers and wetlands. The region’s first major blue-green algae bloom occurred in 2017; many actions have been launched to mitigate future blooms.

Water and Sewer



What are blue-green algae (cyanobacteria)?

Blue-green algae, are naturally occurring microscopic organisms found in both fresh and salt water. Under conditions such as warm water temperatures, high nutrient loads, and other influences, blue-green algae can multiply quickly and create blooms. These blooms can sometimes produce harmful toxins.  Blooms can occur at any time of year, but are more common in summer or early fall.


What does a bloom look like?

Colors may vary depending on the species of blue-green algae, but typically water will take on a green tint. There may be an earthy, musty, or stale odour as well. When the algae rise to the surface it is often described as if the surface of the water has been painted green.

What causes a bloom?

Blooms are triggered by excessive nutrients. This is further accelerated by warm weather, calm conditions and stagnant water.

Why is blue-green algae a problem?

When they occur in excess they can replace other species, creating an imbalance in the ecosystem and deprive other species of food. There are also many varieties and each one reacts differently to treatment.

What can be done to control blooms?

The ultimate solution is to control the input of nutrients. There are products that might be able to help treat a body of water that has a blue-green algae bloom.  

How and when was it detected in the Tower Road reservoir?

The first visible signs of algae appeared on September 12, 2017 during routine maintenance and monitoring of the dam and spillway. On September 15, test results confirmed the presence of blue-green algae.

Although blue-green algae have been detected annually, no blooms developed in either 2018 or 2019.

What is being done to resolve the issue?

The City of Moncton is pursuing mitigation measures both for the watershed and the water treatment plant.  The watershed mitigation recommendation has not yet been approved by the applicable regulatory bodies; further research has been requested of the product supplier.  The water treatment plant is being upgraded in various phases; Phase 1a (building addition) is almost complete, Phase 1b (clarifier retrofit) is expected to be complete by the end of 2020, and Phase 2 (toxin mitigation) has recently begun and is expected to be complete by about 2023.

Could the City have done something to avoid this situation?

Blue-green algae appear naturally and often when the weather is very hot and dry. Unfortunately, that is exactly the type of weather we’ve had over the summer. There is very little that could have prevented this from happening. Irishtown Nature Park and McLaughlin reservoir have both experienced blue-green algae in the past. Many other municipalities in NB, across Canada and around the world have also had this issue; it is a naturally occurring problem.

What will be the cost to fix the issue? How long will it take?

The water treatment plant is being upgraded in phases.  The cost for Phase 1 is about $6M, including assistance from both the federal government (40%) and the provincial government (33%), and the cost for Phase 2 mitigation is expected to be about $22M (applications for funding assistance have been submitted). 

Will it affect our drinking water supply?

Blue-green algae is present in both the Turtle Creek reservoir (our primary drinking water supplyand and in the Tower Road reservoir (second supply opened in 2014).  At the moment, conditions indicate that a bloom may occur in the Tower Road reservoir, as had occurredin 2017.  At this time, residents and pets can consume the water. Should there be a change in the situation, however, the public will be notified immediately.

Is the water treatment plant doing anything? Are they affected?

Water treatment plant operators are continuing normal operations as well as daily monitoring and sampling.  They are also working with the City of Moncton to prepare for if they are impacted by the blue-green algae.

How will we be notified if we are no longer able to drink the water?

The City and Department of Health will notify residents of the tri-community immediately. It will be done through a media advisory, social media, websites and Moncton will also send it through their Moncton Alerts program.

I have a well, am I also affected?

No, homeowners with wells are not affected by the blue-green algae.

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