An Intro to Salt Water Intrusion

After our hot, smoky summer, it might be a good time to take stock of our water situation. The trend seems to be towards longer, drier summers and there were reports this year of lower than normal well levels. We really don’t have enough data to draw conclusions but we are concerned: a dropping water table at the end of summer could be a warning sign. And one of the concerns for a coastal aquifer such as ours is saltwater intrusion. Here is how the BC website on Salt Water Intrusion describes it:

Saltwater intrusion occurs when saline (salty) water is drawn into a freshwater aquifer. Saltwater intrusion can affect one well, or multiple wells in an aquifer, making the water unpotable.

And the site goes on to advise:

Know the risks: Be aware of areas that are at risk of saltwater intrusion and educate property owners, site managers or water system operators that their well or locale could be affected.

Wells closest to the coast are at the highest risk. Many Fanny Bay wells are within metres of the ocean and some are actually drilled to depths BELOW sea level. It’s the weight of the water in the hills above us, the hydrostatic pressure, that keeps the saline boundary from creeping in. If the local water table drops too far we could start seeing saline intrusion.

There are many factors that can increase the risk of salt water intrusion. Increased population is one, as it results in increased water consumption. The population of Fanny Bay increased by 10% in the period between 2011 and 2016. Climate change is another. Climate models for our area predict increased rainfall but wetter winters might not be enough to keep our water table from dropping during longer summer droughts.

While we continue our efforts to learn more about our water supply it certainly won’t hurt for us all to begin developing good water conservation habits.

Leave a Reply

Your email address will not be published. Required fields are marked *