Highlights:

• Rain totals between 60 to 100+ mm.
• Local watercourses have risen and spilled their banks.
• Flooding of the Thames River flats from Delaware down to Thamesville.
• 6th Street Dam in Chatham will need to be operated.
• Flooding of some streets in Chatham adjacent to the river.

Message:

The Rainfall Warning issued by Environment Canada has now ended. Since late Tuesday evening, the watershed has received an unusually large amount of rain for this time of the year. In the lower Thames River watershed, much of the west seems to have received between 60 and 70 mm rain in total. The east of the watershed received higher amounts with rainfall totals between 60 and 90 being reported. Isolated areas received substantially more rain. For example, the Glencoe area received over 100 mm of rain and the Municipality of Southwest Middlesex declared an emergency and closed all roads. The upper Thames River watershed received similar amounts of rain to the eastern end of the lower Thames watershed, with areas in the north receiving over 100 mm of rain. Flows have not yet peaked on the Thames River in London, however, some general predictions about the extent of flooding can be made.

Many local watercourses have reached bank full conditions or spilled their banks. High water on some watercourses should still be expected over the next couple of days, especially in downstream areas that might be influenced by high water on the Thames River.

Flooding of the river flats along the Thames River from Delaware down to Thamesville has already begun. The flooding is expected to be unusually high for this time of the year and will be more similar to a spring flooding event. Water on the river could get high enough to affect the approaches to the bridges across the Thames River in Middlesex and Elgin Counties. At this point in time, the flooding is not expected to impact the community of Thamesville.

It is already clear that the Lower Thames Valley Conservation Authority will need to operate the 6th Dam in downtown Chatham to protect the south side of the city from flooding. The LTVCA is preparing for 6th St. Dam operations beginning tomorrow.

In Chatham, the sidewalk along the river in the downtown is expected to be flooded over this evening. Based on preliminary numbers predicted for the peak in London, there will likely be flooding of several streets in downtown Chatham adjacent to the river over the weekend. Flooding of the basements of businesses along King St. in downtown Chatham is expected. (This typically begins around the same time that 6th St. Dam operations begin.) There is also a strong likelihood that there will be flooding slightly higher than the flood of 1982. This would include flooding on Siskind Court and around the intersection of William and Water Streets. There is also the possibility that there will be more flooding, similar to the 2008-2009 flood. This would also include flooding on Salter St., Thames St. around Pitt St., and Thames Street around Kent St. Currently, peak water levels would be expected in Chatham on Sunday. While there is still uncertainty in these forecasts, given that flows have yet to peak in London, the community should take advantage and prepare early for flooding over the weekend.

People should take extra caution and avoid the river, ditches, and streams. The combination of slippery banks and fast-moving water can be dangerous. Standing water can also present unseen hazards. Children and animals should be kept away from the water.

Officials will continue to monitor the situation and update this advisory if necessary.

This message will be in effect until September 28 or until updated

Message Contact: Jason Wintermute (jason.wintermute@ltvca.ca)