Where Our Water Comes From

First some  Aragon Road Geology

Precambrian time started with the creation of our planet earth 4.5 billion years ago. Three billion years later the earliest life forms appeared.

Remnants of the Grenville Mountains, that towered up to 25 kilometres high more than a billion years ago, are all around us because we are on the edge of the Frontenac Axis, an  exposed strip of Precambrian rock that links the Canadian Shield with the Adirondack Mountains across the St. Lawrence River. The Thousand Islands are the outcroppings of the Frontenac Axis.

Nearer to us, on Colonel By Lake, Esther Head and the stretch of rocky outcroppings towards the Rideau Acres campsite, are reminders of Precambrian times.

The Cataraqui River runs over the falls into a deep valley flanked by steep  Precambrian rocks on each side . The gorge is a result of a fault line.

However, the geology of the Aragon Road, just a little to the north, is very different. The Precambrian period ended about 570 million years ago, followed by a 100 million year period of erosion of the mountains. During that time a thick bed of fine grained conglomerate was laid down that later hardened into sandstone by a cementing action with clay as a binder. This is called the Potsdam group, shown on the geological map below in lightest brown, number 11.

geology kingston area potsdam sand stone col by lake

Note that north of Kingston Mills, shown at the lower left corner,  with the white being Colonel By Lake, the Aragon Road is underlain by the Potsdam sandstone, number 11, and coloured in light brown. But Casey’s Island, the peninsula off Graham’s Park has a different rock base and so does the end of the road at the Alan Point Drive, the darker brown indicates metamorphic rock which is also formed from sediments but has changed its chemical and structural composition because of intense heat and pressure. It would be interesting to know the well-records of houses along the road and at the new Alan Point development. 


Fast forward to the time that our area was covered by glaciers about a million years ago. The glaciers advanced south and retreated north, four times. The last retreat was about 20,000 years ago, “very recent” in the geological timeline. the ice left our area but it plugged the natural route to the ocean, The St. Lawrence valley, and thus a huge lake was formed that reached a high enough level that it started to drain into the Mohawk-Hudson river near Syracuse. The lake called Lake Iroquois was 500 feet deep over Kingston. The melting glaciersDEPOSITED grey silt in the lake.  In the winter, when the water was still, clay that was suspend in the water would sink to the bottom on top of the silt.  When finally, about 11,5000 years ago, the ice dam in the St. Lawrence valley broke, Lake Iroquois began to drain through the valley and it became the St. Lawrence River, the landmass rose and Lake Ontario was formed. In many areas around the lake a fertile mixture of “till”, that is composed of glacial sand and layers of clay, were left behind.

Along the Aragon Road and to the north and north-east is a deep layer of this unconsolidated soil, or till, from the last ice age. It consist mostly of clay with some sand and stones mixed in, some of which are huge boulders and are called glacial “erratics”.

Erratics had been frozen into the glacial ice and were carried over large distances without being worn down or broken up. There are many erratics along the road embedded in the shore of Colonel By Lake and in the soil on the north side of the road at the top of the limestone ledge. Those boulders were from  the fields and  put there by the farmers who moved them to enable plowing.

From lecture-notes by W. Alan Gorman, Professor, Geological Sciences, Queen’s University, at Kingston.



The Potsdam sandstone body up to 450 metres thick and stretching through southern Quebec into the state of New York, is our aquifer. It allows us to live here.

The sandstone structure has micro spaces, in between the grains and clay cement, that hold water. The intergranular porosity of our sandstone ranges from 4-30  percent. The more porous the rock is, the more water it holds. According to a publication by the US government the Potsdam sandstone in NY state which is part the Potsdam group here in our neighbourhood, yields from 3-30 gallons per minute at an average penetration into the sandstone of 33 feet. Fractured granite yields also good water depending on the size of the fractures the amount of water can vary.


Our well-log at 477 Aragon Road issued by William H. Davy and Son, shows a 40 gallon per minute yield at 73 feet. It goes through a layer of clay  31 feet deep, and penetrates the gray sandstone to 42 feet deep.

A little more north and west from us a new well drilled recently showed a layer of 3 feet of brown clay, 80 feet of limestone, 28 feet of sandstone and then 4 feet into the granite. We obviously live on top of a greatly varying local geology.

At Alan Point north-east from us have again another geology with clay and till overburden and bedrock at 15 feet at the “End of the Aragon “limestone house site, bedrock starts at 25 feet at Alan Point . Both wells draw water at about 60 feet  and at 50 feet depth from the fractured bedrock that is specified as sedimentary rock that has been crystallised in hard bedrock.

Along Maple Lawn Drive two test wells were drilled for the new development of five estate houses. One existing well was used in the testing. The well logs showed 23 to 46 feet if overburden of silt and sand from glacial deposits, then lower there is  limestone sandstone and granite. The wells were drilled 85-95 feet below grade, about 60-49 feet into the sandstone or bedrock through a layer of limestone below the overburden,

Will there always be water?

Prior to a housing development the city planning department demands proof of good water and that neighboring wells do not interfere with each other. Tests along Maple Lawn Drive showed that while pumping for 6 hours continuously, and drawing a total of 10,000 to 12,000 litre of water at a rate of about 25 littr per minute while the minimum required yield of the well for these estate houses is 15 litre per minute. The water level in the test wells went down between 0.20 metre in one well to 5 metre in another during this continuous pumping. Normal use would draw considerable less as we don’t draw water for long periods of time. Not if we use our water only for ordinary household purposes and sanitation only.

The effect of the test  pumping on the other wells that were 240 to 400 meters apart was almost nil, between 2 to 14 centimetres.

If we use our wells responsibly we do not affect our neighbour’s well in any meaningful manner.

But there are industries and agricultural businesses that use large quantities of water and they might affect the availability of water for us all. Here are some statistics: Ontario withdraws about 23 percent of available water from aquifers throughout the province. The state of New York draws 34 percent from its aquifers one of which is the same as ours in the Potsdam formation.


The average Canadian, while using  only a few litres each day for personal consumption uses from 250-450 litres of water per day overall. In agriculture one cow would need an average of 90-135 litres per day. That can add up to a lot of water mostly for cleaning milking equipment, stables and so forth.  These numbers are from the booklet “Best Management Practices Water Wells, Ontario


geology photo aquifer house etc

Best Management Practises, Water Wells  shows two aquifers one near the surface which is called an unconfined aquifer and is recharged during days or weeks depending on the permeability of the surface layers. The second one, whichAPPLIES to our wells, is a confined aquifer as it is protected by a “clay aquitard” that, as the name suggests , slows down the recharging to the aquifer. It protects but does not completely prevent our water against contamination. In deep, regional flow systems with long flow paths of tens of kilometres, recharging takes a long time  and water in the aquifer may be thousands or tens of thousands of years old as it is enclosed in the sand stone. 

Our wells penetrate the sandstone aquifer or the fractured granite, which might give us what we would call “pre-industrial” clean water without the modern trace chemicals of surface water. But the aquifer can still be contaminated by abandoned wells that penetrate the aquifer and have not been “plugged” in a professional manner. Some of those did exist north of us but have been located and closed by the City, as far as we can ascertain.

The aquifer can also be contaminated by recharge areas where the sandstone interacts directly with permeable surface layers of cracked limestone or overlaying fractured rocks, as indicated by the blue, red and green arrows.

If your well water is tested positive for coliform bacteria check if the seal around the pipe at the surface is properly “mounded” with clay or earth that directs the rain water and other surface water away from the well. A good annular seal of bentonite slurry, cement grout or concrete is assumed to be in place. See illustration.

geology drilled well

We hope you enjoyed reading this post and found the information helpful. Any questions about your own well or if you know of any abandoned wells, contact us.

If you have your well log handy would you  be so kind to let us know the geology of your property. It is assumed that it will show a deep layer of clay and gray sandstone from which you draw the water. Houses around Alan Point Drive might have a different geology and it would be interesting to know. In the meantime we will explore the well logs of housing developments nearby that have been approved. New developments undergo a hydro-geological investigation to find out if the aquifer beneath it can support more houses.


Post script: citizens in the town of Aberfoyle,Ontario, are fighting a renewal of water drawing rights for Nestles bottling plant. This article in the Globe and Mail makes it clear why. It is interesting to read about the amount of water drawn from that aquifer. For more click HERE.

To go to the INDEX  just click this GLACIAL “ERRATIC”

geology glacial erratic