Conservation Corner: Groundwater, the hidden resource
by Ryan Post

To the eye, water is abundant in Ontario with numerous lakes, rivers, and streams. But have you thought about the water we cannot see - groundwater? Groundwater supplies the residents of the Nottawasaga Valley Conservation Authority watershed over 70% of its drinking and water needs for agricultural, residential, and industrial purposes.

There are good economic reasons for this widespread dependence on groundwater. In its natural state groundwater is usually of excellent quality. It can be inexpensively tapped adjacent to the point of use, thereby saving the costs of transporting water long distances. Surface water, on the other hand, usually requires storage and treatment, which are relatively expensive and pose challenging technical issues. For rural residents relying on individual wells, groundwater often is the only available water supply, and for many communities it is by far the least expensive option for public water supply systems.

So what is groundwater? Unlike popular belief, groundwater is not an underground river or lake. Rather it is water stored in cracks in rocks or between sand grains and is called an aquifer. An aquifer can be defined as a geologic formation or unit that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs.

Groundwater is part of the Earth's water cycle that flows freely underground. Water is received from rain and snow melt. Some of this water runs off directly into lakes and streams. Some is lost to evaporation. The remainder water infiltrates into the soil past plant roots and enters the water table, where it becomes groundwater. Groundwater moves extremely slowly - usually centimetres per day, whereas rivers move swiftly - cubic meters per second.

Groundwater does not stay still, but moves from recharge areas to discharge areas, producing springs or feeding water into streams, wetlands, or other surface water bodies. Recharge areas can also aid in the replenishment of deeper aquifers. The groundwater flow direction generally mimics the local surface drainage with flow regionally towards the Nottawasaga River and its tributaries, or Georgian Bay in the NVCA watershed. Recharge areas in the NVCA are generally located in areas of elevated topography with permeable sand and gravel layers. Major recharge areas include Oro Moraine, the Simcoe Uplands, Oak Ridges Moraine, and portions of the Niagara Escarpment in areas where ice-contact glacial deposits and morainal areas are present.

Areas of groundwater discharge areas include the flanks of the Simcoe Uplands, the base of the Niagara Escarpment, the Minesing wetland, and the Osprey Wetlands.

Activities on the land surface can affect groundwater quality because water seeps from the soil surface to the groundwater table within a few miles of the well. Fertilizers, pesticides, household cleaners, human and animal waste, underground storage tanks, as well as hazardous wastes, can contaminate groundwater. You can help to improve groundwater quality by examining your actions and considering their effects on water quality. Ways to help improve groundwater conditions include conserving water, minimizing household waste, limiting the use of fertilizers and pesticides, and properly locating, constructing, and maintaining wells and septic systems.

Remember that once contaminated, groundwater is extremely difficult, if not impossible, to clean up. Prevention is the key!

"Conservation Corner" is a monthly column that looks at the theory, practices, technology and benefits of land & water stewardship. The NVCA is your public agency dedicated to the preservation of a healthy environment.

As your partner, the NVCA provides the expertise to help protect our water, our land and our future. For comments or suggestions about this column contact Ryan Post, Hydrogeologist, at (705) 424-1479 ext. 249. Those interested in the Healthy Waters program, contact Shannon Stephens 705-424- 1479 ext.239 or visit our website at www.nvca.on.ca.