Resumption of Lake Major water fluoridation could take years

It could be a long time before the Lake Major water supply plant resumes a fluoridation process that has been offline since April 2020.

Limited chemical storage space at the facility is part of the reason why it could take anywhere from a year to 10 years before fluoridation can resume, Halifax's environment and sustainability standing committee heard on Thursday during a presentation by Halifax Water.

The plant provides drinking water to customers in Dartmouth, Cole Harbour, Eastern Passage, North Preston, Westphal and Burnside.

The utility has had to increase the volume of alum it uses to treat the lake water from 200,000 kilograms when the plant was first commissioned in 1999 to more than one million kilograms now.

"That's really driven the need for adding alum into the storage capacity within the plant," Wendy Krkosek, Halifax Water's director of environment, health and safety, told the committee.

Changes in water quality due to the short- and long-term effects of "climate change events and processes" have required increased alum usage to achieve treatment objectives, Halifax Water said in a followup email Friday.

"For example, impacts to the forest in the watershed from Hurricane Juan in 2003 resulted in increased organic loading going into the lake from downed vegetation and then the floods in 2023 resulted in overland runoff that transported organic material into the lake," a spokesperson for the utility said in the email.

"As well, longer-term, over the last number of years we have been observing an increase in organic levels as lakes have recovered from the impacts of acid rain."

Halifax Water is considering three options to reinstate fluoride, a naturally occurring mineral that can help protect teeth from cavities and tooth decay.

The option the utility's staff is leaning toward is one that would move the storage area for an existing chemical called orthophosphate, which is used for corrosion control, to another location in the facility.

"That's an easier product to manage and from an occupational health and safety perspective, so we could move that somewhere else and put the fluoride tank in that place," Krkosek said.

This option would allow for work to continue on installation of an extra alum tank, and would have fluoride back online within two years. It would cost around $1 million.

Kenda MacKenzie, the general manager and CEO of Halifax Water, told the committee that staff are supporting this option "because from a cost and a practicality and earlier installation, we can do that."

The fastest option is to pivot the ongoing alum tank installation so that it could be reconfigured for fluoride, which would get fluoride back online within a year. But this option, which would cost under $500,000, creates risks if there was a change in water quality.

The third option is to incorporate fluoridation into major long-term capital upgrades at the Lake Major facility. This would take five to 10 years to get fluoride back online and cost under $500,000.

Deputy Mayor Tony Mancini, who is also the councillor for Dartmouth East-Burnside, said he supports what staff will be recommending.

"And mainly because it's a two-year time span. Option 3 being five to 10 years? That's a whole generation of kids not having fluoride in their water," Mancini said.

Krkosek said Halifax Water will seek input from its board of commissioners on March 27.

Nova Scotia's Environment Department said on its website that fluoridation of drinking water supplies is "a well-accepted measure to protect public health and is strongly supported by scientific evidence."

Halifax Water has added fluoride at some of its water supply plants since the mid-1950s. It has never added fluoride to its six smaller treatment plants: Bennery Lake, Five Islands, Bomont, Middle Musquodoboit, Collins Park and Silver Sands. 

Fluoridation of drinking water resumed at Halifax Water's Pockwock Lake facility in December 2024 after an interruption of more than a year.

In a post on its website in January, Halifax Water said the fluoride tank at Lake Major was at the end of its useful life and was becoming a safety risk in 2020, which is why the decision was made to take it offline.

Staff began plans to replace it in 2021-22 and a capital project was initiated, but record-setting rainfall events over the summer of 2023 "caused significant changes in lake water quality." Those changes meant more chemicals were being used in the water treatment process to meet compliance obligations.