The City has responded to drainage problems in communities that previously experienced a high frequency of flooding. Drainage work has been undertaken in Mill Woods, Lago Lindo, Dunluce Warwick, Ottewell, Kenilworth, Mayfield, High Park, McQueen and Laurier Heights.

There are two main reasons. Neighbourhoods built before 1980 were not required to have a major overland flow escape route, which carries away rainwater that storm sewer pipes cannot handle. In the absence of an overland flow escape route, flooding may occur in basements and on residential streets. Communities built before 1980 that have natural overland escape routes are also less prone to flooding than other older areas that do not.

Another reason is that storm events are random and tend to be concentrated in small areas. Often one community will be hit with a short duration, high intensity rainfall event that causes flooding. Meanwhile, a nearby community may be hit with the same storm but the intensity is lower and no flooding occurs.

Though this is not common, there could be a number of reasons for this occurrence. One side of the street may have basements that are lower than the other, due to the natural slope of the land. The height differential could be difficult to detect with the naked eye but is enough to cause flooding.

Likewise, in neighbourhoods with back alleys, one side of the street may be serviced with a different piping system than the other. This can result in a slightly different level of service, which may contribute to flooding.

Lot grading, the absence of a backwater valve, incorrect positioning of a downspout, a malfunctioning sump pump, leaking weeping tile, and even the style of home can contribute to flooding.

The level of drainage service is a concern for many communities throughout the city. The City is making better flood protection a top priority and is committed to do what is possible to improve drainage in local neighbourhoods. However, until the engineering studies are completed, it is premature to say what can and will be done for specific neighbourhoods.

Yes. The City will inform affected residents and communities of the engineering studies' findings and will consult on potential flood protection solutions. Community input and support is key because system improvements will require cooperation from the City, individual neighbourhoods and private landowners.