Sinkholes drain lake near Oxford



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

A kilometre-long lake near the town has mostly disappeared as the lake’s water drained into at least two sinkholes.

“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,” she said. “Each time I visit there’s something new exposed.”

Decades-old sinkholes to blame

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.

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)

“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. 

Tied to other Oxford sinkholes

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 the TransCanada Highway 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. 

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