In the last column, I wrote about how flows in the Kettle River aren’t declining over the long term. Some readers then asked why we need to be concerned about water conservation.

So what’s the worry? Three issues rise to the surface: natural variability and climate change; the connection between water at the surface and water underground; and economics.

Flows in the Kettle River are naturally highly variable. The lack of glaciers or big reservoirs means spring floods are much, much higher than the trickle in late summer. Year to year variation makes it hard to depend on surface water supplies, which is why many water users and communities have switched to groundwater where it is available.

Groundwater is simply water stored underground in layers of sediment and bedrock known as aquifers. Groundwater is recharged by spring floods, precipitation and even irrigation. If left alone it slowly flows back to lakes and rivers, over months, years, or even decades.

Flows in the Kettle River and its tributaries are sustained in late summer and fall by this “base flow” from aquifers. But high levels of withdrawals from wells can decrease base flow, even causing streams and rivers to “lose” water to groundwater through seepage. So high use of surface water and groundwater can decrease flow later in the season or over longer periods.

As the growing season lengthens due to climate change, increased dependence on groundwater will likely further decrease the base flow to streams and rivers. Less cool, clean water from the ground means greater stress on fish, as well as less dilution of pollution from our farms and cities.

Increased pressure on groundwater and surface water also affects the water available for other users, which could have economic impacts in some areas. Of course, water costs a lot to treat, distribute, and treat again, and maintaining our water infrastructure is a priority for urban municipalities and irrigation districts alike. So it makes sense from both environmental and economic perspectives that we make the most efficient use of water possible.

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Ask Graham watershed questions at [email protected]. Figures and footnotes are included online at https://kettleriver.ca – look for the menu item “Kettle River Q&A.”

Column originally published in the Grand Forks Gazette on February 13, 2013.