The possible contamination of Whitehorse’s drinking water supplies had the city’s council members up in arms Tuesday evening.

A report from municipal staff members indicates surface water could potentially be occurring in the Selkirk aquifer, which is the primary source of drinking water in the city.

A few husks from the Giardia parasite have been found in samples taken from the aquifer.

According to the staff report, “the city currently withdraws 100 per cent of its drinking water from the Selkirk Aquifer through seven production wells.

“Current treatment consists of using chlorine for disinfection before distributing it throughout the city.

“When the city began exclusively using the wells in 2010 for drinking water, the data indicated the wells were not Groundwater wells Under the Direct Influence of surface water (non-GUDI),” the report says.

All of the seven wells are now under the influence of groundwater, according to city staff members.

The report goes on to state, though, “over the past few years the city has detected changes in the chemistry of the groundwater sourced from the wells.

“These changes include higher pH levels, higher concentrations of iron and manganese, higher micro-particulates and variations in groundwater level, temperature, and conductivity. There have also been three detections of Giardia ‘husks’ (non-live organisms) at one of the main producing wells.”

Due to the growth in the city, additional pressure is being placed on the system.

Any water source being affected by groundwater requires additional treatment under territorial legislation and regulations, the report states.

Upgrades to the Selkirk water treatment plant could cost between $40 million and $55 million.

A Canada Community-Building Fund transfer pay agreement is in place for $2 million to begin detailed design work on the upgrades.

City council members have two basic choices on the matter, the report suggests. They can proceed with the initial design work, or the matter can be referred back to administration for future consideration.

The report suggests the “planned upgrades will provide both a reliable second source of drinking water supply and the ability to relieve volume stress on the aquifer.”

The higher cost estimate of $55 million includes heaters and a sedimentation basin that would allow the city to pull water from Schwatka Lake, the aquifer, or use a blend at any time of the year. The lake was once the city’s primary water source.

“Additionally, the upgrades to the treatment plant will provide a tangible alternative of water supply backup during emergency response scenarios,” the report says.

“Emergency situations may occur when the groundwater production wells get damaged (either mechanical or electrical) or are rendered inoperable due to inadequate water quality, such as from chemical contamination by fuel spills, or biological contamination by coliform bacteria and Giardia.”

The $40-million cost estimate would still allow the city to pull water from Schwatka Lake.

However, it would be at a blended rate of 60/40 surface water/groundwater with no ability for surface water withdrawal in the winter months.

Administration is recommending the city budget for the higher cost of $55 million until the design is far enough along to confirm the option that will provide the treatment and volumes required to support growth until 2040.

Coun. Ted Laking questioned the recommendation to proceed with the $55-million option, worried that would lock the city into a decision without proper consideration.

“Isn’t that essentially making the decision now that the city would be going down that path?” Laking asked.

“If we’re starting design work with that in mind, how would we ever go back?”

He added he believes the project could ultimately go as high as $71 million.

Laking also questioned why the city wouldn’t be looking at relocating the treatment plant wholesale.

With most of the city’s expansion taking place away from downtown areas, on the ridges above the main valley, Laking said, there could be some practical benefits to having a gravity-fed system instead of pumping water uphill.

That would involve a wholesale reinvention of the system, which would be more expensive yet, he was told.

Mayor Laura Cabott expressed similar concerns, saying she was confused about just where the city is in the process.

“This is a big project, an expensive project. Maybe we’re crystal-balling here, but how soon could it happen that all the wells would need some extra form of treatment?” the mayor asked.

She was told an exact timeline couldn’t be provided.

Cabott said last year, some of the preliminary design work was to be done, followed by additional work this year. She said she wasn’t clear whether that had been accomplished yet.

Two preliminary reports have been made, city staff said. The detailed work is now scheduled to begin, with $2 million in place for it.

Cabott also questioned a section of the report that suggests local contractors and businesses might not be able to qualify for the project due to a lack of capacity and expertise.

That could mean the city would have to bring in firms from Outside to do the work.

Deputy Mayor Dan Boyd said, “I think it’s important that we continue on with clarity over this $40 million versus $55 million.

“I think I understand this well, but I’m still concerned this will come back as a $55-million project and the $40 million will drop off the board.

“So how do we manage going forward? What does that look like in the future?”

He was told that would ultimately be a decision made by council.

Council members are to make a decision next week at the regular council meeting.