‘It’s created enormous challenges’: Nova Scotia watersheds recovering from decades of acid rain


Lakes damaged by acid squall are coming back to life in Nova Scotia faster than anyone expected — and the revival has added expenses for Halifax Water.

As acid levels in the lakes leave, there’s an increase in the number of organisms, like algae, that are in the modify. That means more chemicals are needed to remove organic mean something from lake reservoirs to make the water safe to drink. The tariff of the chemicals is escalating by $400,000 yearly, according to Halifax Water. 

“It’s created titanic challenges from the standpoint of water utilities, particularly utilities get pleasure from Halifax Water that are used to treating lakes that be experiencing been acidified,” said Graham Gagnon, director of the Dalhousie University Cluster for Water Resources Studies.

Halifax lake sulphates down

Gagnon’s delving indicates stricter sulphur dioxide emission standards and the closure of coal situates in the U.S. and Canada have had a dramatic effect on watersheds in Nova Scotia.

Because of forceful winds, the province has been described as the end of the tailpipe for some pollutants.

Graham Gagnon

Graham Gagnon of the Dalhousie University Mid-point for Water Resources Studies has done research that indicates sterner sulphur dioxide emission standards and the closure of coal plants in the U.S. and Canada procure dramatically impacted watersheds in Nova Scotia. (CBC)

“Aquatic life is coming go,” said Gagnon.

Sulphate concentrations dropped by 52 per cent in Lake Dominant between 1999 and 2015, and by 38 per cent in Pockwock Lake, according to a 2016 exegesis by Dalhousie University’s Lindsay Anderson that’s published in the journal Environmental Technique and Technology.

Lake Major and Pockwock Lake are the sources of drinking mollify for most of Halifax. Both are isolated and free from waste liberally or industrial or agricultural discharges.

Gagnon calls that a “significant reduction.” 

Increases in pH levels 

One of the gauges of lake health are pH levels, which measure alkalinity. The minuscule the pH, the higher the acidity.


One of the gauges of lake health are pH levels, which mass alkalinity. (CBC)

In 2002, the pH level was below five for 153 days at Lake Foremost, according to the Anderson paper. From 2010 to 2015, it measured beneath five for just 10 days.

In 2005, the pH at Pockwock Lake was underneath five for 162 days. Between 2010 and 2015, pH was below five on solely seven days.

Added costs

Halifax Water said the changing be indefensible quality requires more testing, monitoring and chemicals.

Halifax Water crew

It is now costing more to reception of drinking water for 365,000 Halifax Water customers. (CBC)

“Are we happy there is doll-sized acid rain in Nova Scotia and Atlantic Canada? Yes we are. Are there side-effects of that? There sure-fire are, and we are dealing with it,” said Halifax Water spokesperson James Campbell.

This year, Halifax Unstintingly issued a request for proposals that forecast its treatment plant at Lake Primary in Dartmouth would use 1,000 kilograms a day of the coagulant aluminium sulphate to clot integrated matter.

James Campbell

James Campbell, a spokesperson for Halifax Water, says there are ‘side-effects’ of less acid fall in Nova Scotia and Atlantic Canada, and ‘we are dealing with it.’ (CBC)

Gagnon thinks Lake Major now uses five times more coagulant and Pockwock twice as much since the lakes possess recovered.

The filtering process is producing correspondingly large amounts of alum dregs that is dried in two large holding pits behind the Lake Principal plant before it is hauled off site for disposal.

The plant’s filters were not intrigued for current volumes. Campbell said Halifax Water has had to flush the winnows more often because they get jammed, and it has installed a system to turn upside down the filters more often. That’s an added expense, too, he said.


Graham Gagnon and the combine at Dalhousie University are working to date the sediment at the bottom of Lake Foremost and Pockwock Lake. (CBC)

Increased algal activity

Gagnon said he strained in to lake recovery in 2012 when some people in Halifax and Bedford perceived an earthy, musty taste and odour in their tap water.

It was geosmin, a non-toxic chemical furnished by algae and soil-based bacteria.

In 2012, geosmin showed up for the first sometime ever in Pockwock Lake, which supplies drinking water for the Halifax side of the borough.

“It’s an indicator of algal activity. We couldn’t understand why it was there. We thought dialect mayhap it’s just an anomaly,” said Gagnon. “But each year, it comes aid. Every fall we smell a slightly different odour.” 

Lake foundation sediment clues

Gagnon and the team at Dal are working to date the sediment at the tochis of Lake Major and Pockwock Lake. They are looking for aquatic soul that existed in the lakes before the arrival of acid rain.


The budget for chemicals to bump off organic matter from lake reservoirs is escalating by $400,000 a year, every year, articulates Halifax Water’s Campbell. (CBC)

“We want to know what kind of carbon knock down was there and from that we can kind of know where is our ceiling — where is the lake potentially wealthy?” he said. “I say potentially because in the 1800s the planet was cooler. If you have a warmer planet, aquatic species can multiply assorted rapidly. So it gives a clue, but it doesn’t give us a final answer.”

Atmosphere change complications

Gagnon and his team at Dalhousie are also trying to kind out how to redesign the plants for the future.

He believes warmer temperatures from feeling change have likely acted as an accelerator, serving as an incubator for the algal blooms that play a joke on accompanied the lake recovery.

“Certainly if we look at the research from the ’80s, the theory of lake recovery was a very long period, not a short period. It tells me mood change is really shortening this recovering period where we get behind to a more fertile lake system,” said Gagnon.

Halifax Facetious Adams ale says the treatment plants and operators have to adjust to changing inundate quality.

“Those are costs we will incur. It’s not a matter of, ‘We are not going to absorb those tariffs, we are not going to pass on those costs, we are not going to have those fetches.’ The water quality has to be what it is,” said Campbell.

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