Nova Scotia

Sinkholes drain lake near Oxford

A kilometre-long lake near Oxford, N.S., has mostly disappeared as much of its water has drained into at least two sinkholes in recent months.

'I couldn't believe my eyes at the extent that it had emptied'

A log rests on the lakebed after the water receded in recent months. (Brett Ruskin/CBC)

Waterfront property is a bit harder to find this year in Oxford, N.S.

A kilometre-long lake near the town has mostly disappeared as much of its water has drained into at least two sinkholes in recent months.

"This is pretty shocking," said Amy Tizzard, a regional geologist with the Nova Scotia Department of Energy and Mines. "I couldn't believe my eyes at the extent that it had emptied. Each time I visit there's something new exposed."

CBC has agreed not to name the lake, which is about two kilometres from the town, because officials fear it will attract ATVers and others who could disturb local bird habitats and ongoing environmental studies at the site.

It is the latest sinkhole problem in the area. Two years ago, part of a park and adjacent parking lot in Oxford were swallowed up by a sinkhole. Last fall, the provincial government began investigating possible sinkhole activity beneath a nearby section of the Trans-Canada Highway.

Two aerial images showing a sinkhole (the dark circle), likely responsible for draining part of the lake. The top image was taken in 2020, the bottom in 1939. (Mike Johnson — top image/Nova Scotia Government — bottom image)

Aerial images of the lake show at least one visible sinkhole. Tizzard said the sinkhole isn't new — it has appeared in images dating back to the 1930s — but it appears to have recently reopened.

There is most likely another sinkhole at the other end of the lake, where the water level is also steadily dropping.

Tizzard said the lake is known locally to have fluctuating levels, but the water hasn't been this low since the 1970s.

Exactly where the water is going is a bit of a mystery.

"There'd be a big enough pore space to accommodate the size of the lake," Tizzard said. "So we're looking at caves and fractures or fissures. That's where it's gone. We don't know if it's coming out anywhere yet."

The sudden draining is likely due to the water eroding a layer of gypsum, which would have been acting as a plug. 

Visitors discouraged from coming to the lake

Local residents and government officials are hoping that, although the drained lake is enticing, people will be respectful of the space.

Along the lakebed there are already track patterns made by ATVs ripping through the soft mud. 

The area is home to a series of delicate environmental studies, which could easily be disrupted with a high volume of visitors. 

In 2018, the town of Oxford saw a portion of parkland and parking lot disappear into a sinkhole. That hole is part of the same geological pattern, called "karst topography."

The area has underground layers of water-soluble rock such as salt or gypsum. When water erodes that lower layer, the surface eventually collapses. 

Amy Tizzard stands on the lakebed, overlooking part of the remaining lakewater. Last year the water was up to the tree line. (Brett Ruskin/CBC)

A CBC News investigation last year also found that part of the TransCanada Highway near the town was built over a sinkhole. That spot has required ongoing work to patch and refill the roadway.

As for the lake, it's not known how low the water level will go, or if it might begin refilling.

"It continues to get lower every time I come up here," Tizzard said.

A kilometre-long lake near Oxford, N.S., has mostly disappeared as much of its water has drained into at least two sinkholes in recent months. 2:26

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