Researchers monitoring salt water in wells

Posted on July 26, 2011


Sea water is gradually seeping into the drinking water wells along the Northumberland Strait, a University of New Brunswick researcher says.

While no one’s gotten sick yet the future looks grim, Kerry MacQuarrie said.

Climate change experts warn of rising sea levels, which have the unfortunate side effect of leaving groundwater sources ruined by salt water intrusion.

MacQuarrie is looking specifically at the coastal community of Richibucto, where the water has a history of being too salty. The two-year project is part of the Atlantic Regional Adaptation Collaborative, which is a branch of a larger federal climate change planning initiative.

“We would say that the issue is definitely there in Richibucto now,” said Robert Hughes, an adaptation co-ordinator at the Department of Environment. Hughes manages the province’s various climate change adaptation programs, which includes MacQuarrie’s salt water intrusion project.

While Richibucto’s water is currently well within the Canadian drinking water standards, studying the case could illuminate possible future problems and solutions, MacQuarrie said. When the water does eventually become too salty, Richibucto could serve as the model for other communities’ action plans.

About a decade ago, Richibucto was forced to abandon a well and drill a replacement in a new location when the salt water intrusion became a real issue. It resolved the problem, but the town’s seaside location still puts it at risk.

While salt is essential to a healthy diet, too much can be dangerous. Sodium and chloride occur naturally in groundwater, but high levels can turn the water corrosive and damage household plumbing, not to mention cause a salty taste.

“You can’t drink seawater, as everyone knows,” Hughes said.

But rising oceans aren’t the only cause. Higher demand for water means excessive pumping and the groundwater doesn’t have time to replenish with fresh rain or snowmelt. With nothing to stand in its way, the lower, denser salt water is suctioned into the well’s reserves.

“The concern is that if salt water really gets into those aquifers, it’s pretty much there. It doesn’t go away again. That groundwater area is no longer useful,” Hughes said.

MacQuarrie is measuring sodium and chloride levels in Richibucto’s wells with his project partner Karl Butler, a geophysicist at UNB.

Working with two of the university’s master’s students, they shoot electric currents about the power of a car battery through the water. Electricity passes through salt water more easily than fresh water, so the measured conductivity indicates daily levels. The technique is well-established and causes no harm to humans or the water, MacQuarrie said.

With their data in hand, MacQuarrie and Butler then create 3D worlds on their computer screens in which they control a well’s hypothetical pumping rate or possible sea-level rise, among other variables, and see the effect. They also assess where the salt water is beneath the surface. Combined, the findings could be the basis for an action plan.

The project ends around next March or April, MacQuarrie said.

Previously published July 20, 2011; Telegraph-Journal

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