Joshua’s Creek Flood Mitigation Opportunities Study

• The Joshua’s Creek Flood Mitigation Opportunities Study results show that Joshua’s Creek has a lower chance of flooding compared to other creeks in Oakville. Most of the flood risk happens during a major storm like the 1954 Hurricane Hazel, which is also known as a regional storm event, which has less than a 1 per cent chance of occurring each year.
• The Joshua’s Creek Flood Mitigation Opportunities Study recommends  flood emergency preparedness in the short term and upgrading the Metrolinx rail track that crosses the creek in the future, along with incorporating green infrastructure elements.
• The Joshua Creek Flood Mitigation Opportunities Study looks only at flood risk during various levels of storm events. Creek erosion and bank stability are part of the town’s creek condition assessment studies that are completed approximately every five years. 
• Creek erosion rehabilitation along Joshua Creek is currently identified within the town’s 10-year capital forecast with design work to get underway in the next few years.   

The area along Joshua Creek where the Metrolinx rail tracks cross the creek (near Cornwall Road and Ford Drive) is owned by Metrolinx. 

This means that any flood mitigation upgrades, improvements, or replacements to the rail crossing area will have to be managed by Metrolinx, and not the town. Currently, Metrolinx has no immediate plans for any work at this rail crossing. 

The study recommends that the town engage in long-term collaboration with Metrolinx to ensure that increased water flow capacity is incorporated into their future works design.

The flood wall will be constructed entirely on public property, starting at the trail entrance on Constance Drive and extending approximately 350 metres downstream. It will be designed to a height capable of containing flood elevations from a regional storm event and withstand the force of flood flows. 

The flood wall will undergo further analysis during the detailed design phase to ensure that the creek modifications do not adversely impact flooding in the area. All necessary steps will be undertaken, including review and approval from Conservation Halton. 

When assessing various alternatives, the town considered costs at an overview. Financial planning is currently underway through the town’s Rainwater Management Financial Plan. 

This plan will build upon results of various stormwater, riverine, harbour/shoreline and creek studies to evaluate risk, cost per property, and service benefits to prioritize projects for a 30-year stormwater infrastructure plan and assess funding options.

During the flood mitigation study, various alternatives were identified and screened based on functionality (technical merits) initially.  Shortlisted alternatives were then comparatively assessed based on the natural environment, social environment, and  economic considerations. 

A summary of the alternatives, and the preferred alternatives are provided in the Council Report - August 13, 2024: Joshua's Creek Flood Mitigation Study.

The Ministry of Transportation has specific criteria for evaluating drainage and creek crossings along highway corridors such as along the Queen Elizabeth Highway and is not covered in the town’s study. The province is the decision maker on those arrangements.  

Similarly, for privately owned commercial and industrial properties such as the Ford car plant, which is close to the creek, flood mitigation is managed by those respective organizations. It does not come within the town’s study scope. It is the town’s current practice that capital tax dollars are not used for improvements on privately owned lands. 

The Joshua Creek Flood Mitigation Opportunities Study looks only at flood risk during various levels of storm events. Creek erosion and bank stability are part of the town’s creek condition assessment studies that are completed approximately every five years. 

The last assessment was carried out in 2021, and the next one will be in 2026, where the town will assess and document the condition of the creeks and identify maintenance or rehabilitation requirements such as the removal of debris jam and develop a prioritized list and schedule of rehabilitation projects to include in the town’s capital budget.

Routine maintenance of town-owned creeks, including clearing accessible blockages, is conducted year-round. Town staff address issues such as debris jams caused by woody debris, fallen trees, and garbage.

For inquiries or to report debris jams in the creek, contact ServiceOakville by  email at service@oakville.ca or by phone at 905-845-6601.

The floodplain modelling has built in future growth of construction across the town. All new developments are designed to meet stringent requirements in line with the Ministry of Environment, Conservation and Parks (MECP) guidelines and best management practices. Developers must follow policies that control both the quantity and quality of runoff, ensuring no negative impacts. 

For example, new and future developments north of Dundas Street are designed to comply with the North Oakville Creeks Subwatershed Study (NOCSS). This often includes end-of-pipe controls, such as stormwater management ponds, which are sized to manage regional storm peak flows and prevent increased flooding downstream. 

Similarly recent development south of Upper Middle Road and east of Joshua Creek Drive have been built to drain to a stormwater management pond before outletting to Joshua’s Creek.

Resources for property owners and residents are available on the town’s Flooding page, the Region of Halton, Conservation Halton, as well as the Intact Centre on climate change adaptation from the University of Waterloo  .  

The town is collaborating with the Intact Centre to develop a tailored Oakville Home Flood Education and Protection Program (anticipated in 2025). It will promote proactive flood preparedness among Oakville residents by offering educational resources, helping homeowners reduce flood risk and minimize damage during floods.