Oak Ridges Moraine: Introduction

The Oak Ridges Moraine (ORM), about 1400km2 of glacial moraine, is located in the northern margin of the greater Toronto area (GTA) of Southern Ontario.  It is a west-east trending belt that ranges from 5km wide to 20km wide and extends about 140km eastwards of the Niagara Escarpment.  Most importantly, the ORM is a large regional aquifer that provides base flow to over 30 major streams and is the drainage divide between Georgian Bay and Lake Ontario.


The ORM is an attractive location for aggregate companies to mine because of the way glacial sediments were deposited, allowing easy and inexpensive extraction. Aggregate companies also provide many short term benefits for the local economy and government.

 I advocate that the long term costs outweigh any short term gain.

Rehabilitation efforts of the ORM land are being made;  but there are irreversible environmental damages that occur due to the mining processes.  One of the most prominent irreversible impacts is the impact on water filtration.  Typically the ORM land has a very high ability to filter water, allowing for a clean drinking water source for both human and wildlife populations.  The people who live in rural communities are having their water security threatened due to changes in ground water.  The permeability of the ORM sediment allows precipitation runoff to flow on the landscape in a predictable, manageable manner that reduces the risk of flooding.


Although the short term gains of aggregate extraction can be significant, there is a continued focus on how the ORM’s original function is more beneficial than short term gains that are provided by aggregate extraction.

The purpose of this series is to examine the environmental and social and economic benefits of the ORM, and compare them to the ORM’s environmental significance, with a focus on water management.


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