The rain in Spain stays mainly in the plain.  But what happens to the rain on Mayne? 

You can learn all about it in the informative presentation from 2021 by William Shulba, Freshwater Specialist with the Islands Trust, who shared with the Conservancy the modeling work that has been done to better understand freshwater recharge potential on Mayne Island. 

Click here for the recorded presentation.

Here are a few points that I found fascinating in this presentation:

  • While there is enormous runoff of water during the winter rains, William has documented how much of the rainwater actually recharges the groundwater on the island. In addition to rain, snow and fog also help recharge our five aquifers.     
  • Did you know that Mayne weighs more in winter than in summer, and that the weight of the island affects the pressure in our wells? Our topography also plays a part in the pressure in our wells.
  • Saltwater intrusion is a real problem for wells close to the ocean, even when the wells are below sea level. That’s because the pressure of the saline groundwater under the ocean is greater than the pressure of the freshwater groundwater.
  • The water on Mayne is not just essential for us humans; ecosystems are using the water too. Healthy forests and thirsty trees support groundwater recharge and support soil moisture. How? Not only do trees and other plants keep soils moist, but their roots help slow and spread the flow of surface water during rainfall events. This allows the water time to seep into the ground and reduces erosion from fast moving water.
  • While you may have heard the rumour that our groundwater comes from snow melt on Mount Baker, it doesn’t. Mayne is surrounded by salt water and under the ocean is saline groundwater, making it impossible for freshwater to come from off-island.

So, on the next rainy day, take the time to watch this presentation and absorb a few drops of wisdom about our groundwater – all puns intended! 


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