In April 2019, following widespread flooding along the Ottawa river, the federal government warned that extreme flooding is now the new reality of climate change in Canada and that Canadians need to think more about adaptation and mitigation. This year, spring flooding due to heavy rain and snowmelt alone accounted for close to $208 million in insured damages across Eastern Canada. In 2018, severe weather accounted for nearly $2 billion in insured damages, the fourth highest on record. The federal government's disaster support program has paid more in the last six years than it did in the last 40 years. With the cost and frequency of flooding on the rise in Canada, adaptation and mitigation are essential, however, these efforts are often ineffective due to inaccurate and out of date flood plain maps.

Flood plains maps are useful tools used by governments, developers, insurers, and homeowners to assist in determining whether a property is at risk of flooding. However, a map's effectiveness is only as good as the accuracy of the information contained within it, and unfortunately the vast majority of flood maps in Canada are well out of date and do not account for our changing climate. As a result, the lack of any accurate data is putting property owners at a substantial risk, even leaving some properties uninsurable.

In 2016, inaccurate flood data contributed to a $900 million class action lawsuit by residents in the Muskoka region. Following extreme weather, Muskoka property owners sued the Ministry of Natural Resources and Forestry for failing to adequately manage water levels in the Muskoka watershed. The lawsuit claimed that the province failed "to collect, calculate, analyze or inspect data properly, or in a timely manner, to estimate water levels in the Muskoka Lakes in the winter of 2015 through to the spring of 2016."

Another growing area of concern is how inaccurate flood data might affect the housing market. In Canada, a vendor need only disclose a latent defect if they are aware of it. A latent defect is described as one that could not be identified by any reasonable observation and that is potentially dangerous or could render the property unfit for habitation. Disclosures of latent defects do not necessarily impede the ability of homeowners from selling their homes, however, they do have the potential to deter buyers. While a history of flooding is typically considered a latent defect, a vendor may defuse a buyer's concerns by providing current flood plain maps that might list the property at little or no risk of flooding. In reality, the property might be at considerable risk of flooding, something not properly reflected in outdated flood plain maps that do not account for climate change.

Consequently, flood maps have enormous implications on the property value and insurability of a home. For example, in Ontario the Provincial Policy Statement does not permit for developments to occur on lands at a high risk of flooding. By definition, development includes the construction of new buildings, including new structures such as decks, walkways, garages, and expansions on existing buildings. In other words, once a property is designated as high risk, the property owner loses the ability to rebuild, make repairs, and in some cases acquire insurance.

In Quebec, new flood plain maps are already causing considerable frustration among property owners. Like Ontario, Quebec has a policy that bars property owners from building on areas with a high risk of flooding. Following the spring 2019 flooding, the Quebec government imposed a freeze on repairs to homes that sustained more than 50 per cent damage in 2017 and 2019, as well as any homes in a high-risk flood zone. When new flood maps were released in 2019, 120,000 homes in Quebec became subject to that freeze. During consultations in July, angry residents fought to have their homes removed from the new flood maps, despite the fact that the areas were flooded in 2017 and 2019. Their efforts resulted in 30 municipalities being removed from the province's flood zones.

While updating outdated maps is important, it is equally important that the maps be accurate. Maps relying on complaints rather than on science only ignore the present and future reality of climate change placing residents at continual risk.

In 2016, updated and accurate flood maps could have saved a man from losing his house in a flood. The incident occurred after the land survey the man received from the previous owner upon sale of the house showed the house was not in a high-risk flood zone. Unfortunately, the land survey was no longer accurate because it was based on high-water projections made in 1995. In order to rebuild his house, the City of Laval required the man to hire a surveyor to draft a new map – that map designated his entire house at high-risk. As a result, the province would not allow the man to rebuild.

With the risk and cost of flooding steadily on the rise, Canada is busy looking at ways to mitigate and prevent future flooding. One method that Canada is employing to combat flooding is the Disaster Mitigation and Adaption Fund (DMAF). Created in 2017, the DMAF is a federal initiative that will invest $2 billion to support large-scale infrastructure projects to help communities better manage the risks of disasters triggered by natural hazards. Recently, $11.4 million was allocated from the fund to assist Fredericton and surrounding communities from flooding.

Even in areas where flood mitigation efforts are underway, however, there may still be reason for some residents to be concerned. For example, in 2013, the community of High River suffered one of the worst floods in its history, affecting more than 14,500 homes, and leading to the Alberta government to offer to buy and tear down more than 250 severely damaged homes. In total 94 properties were bought out at a cost of $97 million to the province. In 2014, Alberta announced more than $600 million towards flood mitigation. In 2018, however, a couple in High River, Alberta, sued over the impact flood mitigation would have on their property. In a $20 million lawsuit, the couple claimed that the proposed Flood Mitigation Program would flood their property, including their residences, and cause significant property damage and unreasonable risk to human health and safety.

It is starting to become clear that mitigation efforts will come at a cost, leading to more disputes and more potential lawsuits. What is not yet clear is how these efforts will affect most Canadians. Currently, flooding in Canada only affects a small portion of the population, yet mitigation and preventative measures are important because the cost is borne by all Canadians.

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