The Town of Oakville is undertaking a detailed study of the Joshua's Creek system south of Upper Middle Road to Lake Ontario. The focus of the study is to identify flood-prone sites in an effort to determine the most viable and responsible mitigation options to reduce flood risk.
The study is being carried out in accordance with the Schedule B project requirements as described in the Municipal Engineers Association’s Municipal Class Environmental Assessment (EA) document (October 2000, as amended in 2015), approved under the Ontario Environmental Assessment Act.
Town staff are seeking public input related to this project, including alternative mitigation measures, evaluation and evaluation criteria, and any other concerns. This is the second public consultation opportunity for the Flood Mitigation Opportunities Study.
Joshua's Creek Flood Mitigatigation Opportunities Study Presentation:
Comments or questions for the public information centre #2 are due on November 5, 2021. All comments will be reviewed to confirm the preferred alternative. The final Project File Report will be finalized and will be put forth to Council in early 2022. Following Council endorsement the Project File Report will be posted for a minimum 30-day public review period to solicit any final comments and feedback from interested parties.
Several riverine flood mitigation studies either have been completed or are nearing completion within the next six to 12 months, which will have recommendations that will also have budgetary demands on the town’s flood mitigation program. These studies include Munn’s Creek, Fourteen Mile /McCraney Creek, Lower Morrison and Wedgewood Creek and Sheldon Creek. Once all studies are completed, a prioritization of flood mitigation works will be carried out and implemented with consideration of level of risk, return on investment and funding availability.
Stormwater runoff makes its way to Lake Ontario through the town's stormwater drainage system and private drainage systems. The drainage system is split into two components, the minor drainage system and major drainage system. The minor drainage system includes inlets, catch basins, storm sewers, ditches, swales, and driveway culverts, which are typically sized to handle more frequent storm events such as the one in five year storm event. The major drainage system handles flows that are too large for the minor system resulting from infrequent storm events. The major system includes overland flow routes such as road right-of-ways, man-made diversion channels, and natural waterways.
The 100 year storm flood model is based rainfall data from the Toronto Bloor Street station, which has continuous rainfall data for the last 50 years. This storm event has a one per cent chance of occurrence in any given year. The Regional Storm flood model is based on rainfall that occurred during the 1954 Hurricane Hazel flood event. This event saw 285 millimetres of rainfall in 48 hours. The 100 year storm event adjusted for climate change utilize projected rainfall data based on future greenhouse gas impacts for 2080. The Regional peak flow rate is more than two times greater than the 100-year and 100-year climate change peak flow rates within Joshua’s Creek.
All new development must be designed to ensure that there is no increased risk to flooding. This is carried out by ensuring that flows from a site are controlled through stormwater management best management practices such as incorporating on-site ponding areas and detention tanks into the design.
All new and future development north of Dundas Street must meet the requirements as dictated in the North Oakville Creeks Subwatershed Study. Stormwater for development utilizes end of pipe controls such as stormwater management ponds that are sized to control the Regional storm peak flows which are roughly two times greater then 100 year peak flows. This provides the necessary protection to prevent any increases in flooding as a result of the development in the north. Stormwater management ponds also provide water quality treatment and erosion control measures to prevent impacts downstream.
Routine maintenance of town owned creek blocks are carried out throughout the year, including removal of debris jams resulting from woody debris from fallen trees, debris and garbage.
If you see concerns with debris jams in the creek, you can report this information to Service Oakville by email at email@example.com or by phone at 905-845-6601.
The Joshua Creek Flood Mitigation Opportunities Study looks strictly at flooding issues. The town carries out creek inventories to assess conditions and identify risks to infrastructure and property to develop implementation plans and prioritize erosion mitigation works on Town-owned watercourses. The last inventory was conducted in 2015 and is currently being updated for 2021.
Please direct all comments, concerns, and input on this project to the following contacts via e-mail or mail by November 5, 2021.
Diana Friesen, BSc. C.E.T
Water Resources Technologist
905-845-6601 ext. 3904
Janusz Czuj, P.Eng.