The water quality in Bedford’s Sandy Lake has declined to “precarious levels” and action is required even without development planned for the area.
That’s the finding of retired Dalhousie University biology professor Dr. David Patriquin. Since 2017, he’s been monitoring the lake as a volunteer with the Sandy Lake Conservation Association. That work is now also being conducted in collaboration with HRM’s LakeWatchers Water Quality Monitoring program.
Patriquin made a presentation about the state of Sandy Lake to North West Community Council on Monday.
“The water quality has already declined to precarious levels and really needs action now, even without further development. But further development is a problem on top of it,” he told councillors.
“The lake needs attention now. That’s what I’m saying. That the lake is in a precarious condition.”
Observed from the air, Patriquin said the lake appears very healthy.
Surrounded by old Wabanaki-Acadian forest, the waters are clear. The lake and surface waters and wetlands are home to an abundance of wildlife. Otters, frogs, common loons, and fish are among those that call it home. Sandy Lake Beach Park is also a popular spot for swimmers, paddlers, and fishers.
‘Raised some alarm bells’
In 2017 Patriquin conducted a limnological profile of the deepest spot in the lake.
“That raised some alarm bells,” he said.
His concern was over the low oxygen and elevated salt concentration found in the lake’s hypolimnion (lower layer of relatively stagnant water).
“It’s beginning to get salt stratified. You’re getting a saltier water sitting at the bottom. Normally in the summer, the lake is thermally stratified. (In) a deep water lake, the surface water is warm and deep waters are cool and there’s what they call a thermocline (transition layer) in between it,” Patriquin explained.
“But now in addition, we’re getting this chemical stratification. So, that was a bit of an alarm. The other thing was the oxygen, because we like the oxygen to be at a pretty high rate to the bottom. And in a so-called healthy lake it is. But in Sandy Lake, it’s been going down to lower and lower numbers.”
‘Lake quality will deteriorate’
Despite the limited data, Patriquin said it’s clear big changes have occurred in deep water (bottom) dissolved oxygen and in both top and bottom conductivity over the 51-year period.
Of particular concern, he identified the progressive decline in bottom oxygen values from 5.0 mg/L in 1979 to 1.18 m/L in 2022.
“The continuous decline in deep water oxygen over time with levels below 2 mg/L reached in 2022 should be alarming,” Patriquin wrote in a March update to his comprehensive report on the lake’s oxygen levels.
In the update, published on the website Sandy Lake and Environs, Patriquin also wrote that “If this trend continues, the lake could go fully eutrophic and ‘skunky’ in the not-very-distant future.”
Patriquin said planned development to the southwest of the lake would have the largest impact on its water quality.
“You can see with those predictions that with increasing hard surface, it’s very predictable the lake quality will deteriorate,” he said.
Patriquin wrote that ongoing and approved development in the area would increase the settled area from about 29% of the watershed in 2014 to about 45%. He said it would also involve loss of a “significant wetland” in the headwaters.
“Climate warming is another emerging stressor,” he wrote.
‘We know development is coming’
Bedford-Wentworth Coun. Tim Outhit said while any new development would exclude wells and septic tanks — a source of many water quality issues over the years — some development is still in the cards.
“We know development is coming because the desire to stop development has been taken away from HRM. It’s like Eisner Cove and other places. It’s been taken away by the province and fast tracked for development. We don’t like it,” Outhit said.
“God knows the park has increased by 20% during my time on council when we’ve had no development in the area, which I’m very proud of. But development is coming and this level of government can’t stop it. What I want to know is what do you suggest for the type of action that could be taken.”
Outhit wanted to know what could be done to help protect the lake despite planned development in the area.
“Currently, I think we have to clean up what issues we have. One is the sewage treatment,” Patriquin said. “Another one is the trucking operation off of the Dairy Road. That water coming in from there is very polluted. So I would say, you know, a survey to reduce those inputs.”
Lower Sackville Coun. Paul Russell wondered about the source of the increased salt content in the lake.
Patriquin expressed his belief that much of it was likely coming from Hammonds Plains Road. He said using less brine on the roads certainly wouldn’t hurt.
Sackville Rivers Association past president Walter Regan asked councillors to recommend Sandy Lake’s sub watershed be mapped and gauged for a floodplain, “especially after what we heard (from Patriquin).”
Russell agreed to look into it.