How to Protect the Aquifer & Your Well
Most islanders depend on well water for sustained water supply. But as the demand for water increases and more water is pumped from the aquifer new challenges arise with well water quality like sulfur taste and odour, low yields, or saltwater intrusion.
What is saltwater intrusion?
The freshwater aquifer near the coast or on islands like the Gulf Islands is becoming more at risk of saltwater intrusion. Especially in areas close to the coast with a high density of wells, the risk of seawater intrusion into the freshwater aquifer is higher.
Close to the coast, groundwater consists of a freshwater aquifer that sits above the higher density seawater with a transition zone (a mix of fresh and saltwater) in between. Mobile: click on image for description:
The aquifer is affected by
- seasonal variations in groundwater levels,
- amount of groundwater recharge from the rain, and
- the rate of groundwater pumping.
When the pumping rate is too high or when the well is too deep, it can result in saltwater intrusion into the well.
In fracture bedrock, saltwater can find its way to the well via a single fracture.
Once seawater intrusion occurs, changes in the aquifer may be irreversible or may take many years to recover.
Find out more about saltwater intrusion from the Government of British Colombia’s website which gives advice about Best Practices for Prevention of Saltwater Intrusion.
How can you protect your well and the freshwater aquifer?
Saline water is harmful to people with high blood pressure and can cause damage to soil and vegetation. An increase in island population or farming can lead to wells over-pumping and cause saltwater intrusion into the freshwater aquifer.
If you have issues with seawater intrusion into your well or a low water yield, find out more about the recommended well management practices and consider implementing the following solutions:
- installing a water storage tank (cistern) and pumping in water from the well in the wet season (winter) for use in drier periods (summer),
- installing a rainwater collection system, collecting rainwater during the wet season, and augmenting your well-water supply with rainwater during the summer.
We can help determine how big your storage tank should be to meet your water demand for gardening or hosting relatives and visitors during the summer.
by Grazyna Chrobok, M.Eng.,P.Eng.