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Sable Island has fascination for Greenwich freshwater expert

An aerial view of fabled Sable Island, which is home to about 500 wild ponies.
An aerial view of fabled Sable Island, which is home to about 500 wild ponies.

GREENWICH, NS – Hydrogeologist Terry Hennigar is one of the few people who’s stood on the end of Sable Island and felt the spit of land vibrate.

A Sable Island pony digging for water.

“That movement, that’s the surf pounding on the loose sand,” he said to himself. “That is scary.”
Hennigar was on Sable this past summer as a ground water specialist aboard an Adventure Canada cruise, but his history with the island goes back over 40 years.
In 1971 when Mobile Oil expressed an interest in the sand spit on the edge of the continental shelf, Hennigar was the provincial staff member who was asked to check out fresh water supplies.
“I jumped at it,” he said, “and several days later we were putting in the first of a number of freshwater exploratory wells across Sable Island.”
Conducting sampling and exploratory work on the island that was first inhabited by life saving crews in 1801, Hennigar knew that potable water pooled in certain places, but nobody knew how much there was or the chemical quality.
Precipitation is the source of all Sable freshwater. Long-term records indicate increasing annual rates of precipitation between 1941 and 2010, but variations annually of over 70 per cent.
“It was a unique project in more ways than one,” he recalled. “Only so much water can be taken out of the system before salty sea water rushes in.”
The whole Hennigar family spent five summers camped on Sable during the 1970s, which explains his special attachment to the island.
He knows that between the dunes are many depressions usually filled with freshwater and supporting a variety of aquatic plants. These small ponds are most numerous near the west end.
A ten-kilometre long saltwater lake was located on the south beach about midway along the island is now filled with sand.
Approximately 40 per cent of the fresh water evaporates or is lost to vegetation, the Greenwich resident noted. Another 40 per cent simply flows into the ocean. He estimates that less than 20 per cent, roughly, can be withdrawn from the island reservoirs.
Last year, together with provincial employee Gavin Kennedy, Hennigar looked at the precarious nature of freshwater resources on the island. That is why the independent consultant was invited to go along this summer as an expert on the tour boat.
The vessel, Ocean Endeavour, anchored two kms off shore and zodiacs took the 200 passengers to the island on four different days.
Home to over 500 wild ponies and the ghosts of pirates, sailors and convicts, there is lots to interest visitors. Known as the ‘Graveyard of the North Atlantic,’ Sable is also a nesting area for sea gulls, terns and the ipswitch sparrow.
Returning once again, Hennigar allowed, “was a dream for me.”
It was a dry summer on Sable and the horses were sometimes challenged to find fresh water. Hennigar watched one animal dig in the sand a long time with his hooves, then give up and drink seawater.
In the future, he and Kennedy are recommending more studies, including long-term monitoring of water level trends, to support the sustainable use of groundwater on the Sable Island.
“More research needs to be done,” he says, particularly around human contamination from the past.
“Fuel spills percolate down in a matter of minutes into the sand. We need to manage the water supply,” Hennigar believes. “It has to be first class due diligence.”
Hennigar will be presenting a paper at the second Sable Island conference on the Science and History of Sable Island in October. It will take place in Dartmouth and is being organized by the Friends of Sable Island.
According to Hennigar, many people have been captured by the mysterious magnetism of Sable. “It’s so dynamic. There are no trees, just these moving sand dunes.”

Did you know?
Late in 2013 the Sable Island National Park Reserve became officially protected under Canada’s National Parks Act as its 43rd National Park. The island is situated 300 km east-southeast of Halifax.
Parks Canada assumed full administrative control of the island and continues to assess its ecology and biodiversity. The island is staffed year round by six researchers and parks staff, rising to 25 during summer months when research projects and tourism increase.

http://sableislandfriends.ca
 

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