Response to article by Bayshore Broadcasting

On September 5th, I presented about the Karst confluence threat to Bruce County Council. Bayshore Broadcasting reported on this delegation. The article gets core points right, but there are several inaccuracies that I would like to clarify. This is the letter I sent to them.

The original article here: https://www.bayshorebroadcasting.ca/2024/09/10/186973/

Dear Bayshore Broadcasting,

Thank you for publishing an article on my deputation to the Bruce County council. I appreciate your interest in what I consider a serious matter.

There are several factual inaccuracies in your article that could confuse readers and cause harm. I’d like to correct these inaccuracies and hope you’ll publish these corrections, ideally linked from the article.

Fractured (cracked) and karstic (soluble) bedrock behaves somewhat like Swiss cheese – random conduits run through the entire bedrock layer. The movement of water in such bedrock is unpredictable and can change dramatically depending on water levels. This Silurian-era bedrock underlies much of Bruce and Grey counties, usually covered by layers of loam, sand, clay, gravel, or other materials. Some areas are also protected by vegetation that helps filter contaminants through root systems. However, between Tobermory and Meaford, this protective layer is less than two feet thick—often only a few inches. Further south, it becomes thicker, especially between Hanover and Southampton and northeast of the Greenock Swamp. Yet, across the region, pockets exist with little to no protective overburden (see Provincial dataset “Bedrock Topography and Overburden Thickness / MRD207”).

Walkerton, despite having 20-40 meters of protection, still has areas with less than one meter of soil covering the bedrock. These pockets allow contaminants to enter the groundwater through the fractured bedrock, posing a threat to human health. Without this geological risk factor, the Walkerton tragedy would likely not have occurred. In other areas, particularly along the Lake Huron shoreline, the protective layer is primarily sand, which allows contaminants to move quickly. For comparison, in Waterloo and Guelph, the groundwater-carrying bedrock is covered by 100-200 meters of protective material—a much more effective barrier.

With this technical context in mind, here are a few clarifications on points in the article:

• Well Risk: Wells of any depth drawing from the Silurian bedrock are at risk—not just shallow or dug wells. Contaminants can move from the top to the bottom of this bedrock layer in hours, depending on water levels. In Niagara Escarpment Karst regions, researchers have measured contaminant flow up to 2 kilometers per day (Borchert et al., 2021[1]). Therefore, I cannot limit my concerns to shallow wells.
• Contaminants: I highlighted two types of contamination in my presentation: (1) pathogens from manure storage or application on bare fields, and (2) nitrates from manure silage or chemical fertilizers. The conversion of land from permanent vegetation to annual cash crops increases the risk of nitrate contamination, especially when fields lack plant cover for part of the year. This is critical because provincial water testing does not routinely test for nitrates, despite it being a simple test.
• Grey County’s Impact: Severances in Grey County alone don’t affect Bruce County’s groundwater. However, large-scale land use in Grey County can impact Bruce County’s water, as groundwater generally flows westward from the Niagara Escarpment toward Lake Huron.

The main recommendation was to form a task force on rural drinking water protection. While the Drinking Water Source Protection Committee under the Clean Water Act focuses on municipal water, private well water is solely the homeowner’s responsibility. Still, the groundwater supplying these wells remains a public responsibility. Both the agricultural and public sectors are liable if citizens cannot access safe drinking water, which is protected under Ontario’s Environmental Bill of Rights—though only the Ontario Superior Court can officially determine this liability.

Being proactive is essential. If local governments and farmers act now, they can ensure due diligence, avoid liability, and have a say in how rural drinking water sources are protected. Otherwise, if significant contamination occurs, policies may be decided by a court rather than the community. I urge the local community to form a task force. Other regions have developed policies and financing to help farmers transition to Karst-appropriate methods. For example, in Europe, farmers receive payments for protecting ecosystem services like drinking water provision, ensuring predictable income. What prevents us from sharing the financial burden for these more costly farming practices, especially in regions so vulnerable to contamination? No farmer or farm operation should face these challenges alone.

Sincerely,

Thorsten Arnold, PhD

[1] Borchardt MA et al., Sources and risk factors for nitrate and microbial contamination of private household wells in the fractured dolomite aquifer of northeastern Wisconsin. Environmental Health Perspectives. 2021 Jun 23;129(6):067004.

I also sent a simplified version of this letter, in Grade 9 language.

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Dear Bayshore Broadcasting,

Thank you for covering my deputation to Bruce County council. I’d like to point out some inaccuracies in your article that could mislead readers and cause confusion.

Karst bedrock in our region acts like Swiss cheese with random water pathways. Water can move unpredictably, and quickly, especially when levels change. The protection layer above this bedrock is often very thin—sometimes just a few inches—making our groundwater extremely vulnerable to contamination from manure and fertilizers.

Key corrections:

• Well Risk: All wells drawing water from Silurian bedrock—whether deep or shallow—are at risk. Contaminants can move through this bedrock quickly, even traveling up to 2 km per day in certain areas.
• Types of Contamination: I mentioned two contamination risks: (1) pathogens from manure storage and application and (2) nitrates from manure and fertilizers, especially on bare fields. The increased use of cash crops without year-round root cover heightens the risk of nitrate contamination.
• Water Flow: Groundwater flows west from the Niagara Escarpment toward Lake Huron, so large-scale land use – not severances – in Grey County can affect Bruce County’s water quality.

I urged the creation of a task force to proactively protect rural drinking water. While homeowners are responsible for private wells, the groundwater itself is a shared resource, and the public sector has a role to play. By working together, we can protect our water and avoid the legal battles that could result from contamination.

Other regions, especially in Europe, already have systems where farmers are paid to adopt water-protective farming practices. With yearly payments, farmers receive a predictable income for offering ecosystem services. We should consider sharing the costs of these practices to protect our vulnerable water resources here in Ontario!

Sincerely,
Thorsten Arnold, PhD