This from the Lower Thames Valley Conservation Authority:
Last night an ice jam formed downstream of the city of Chatham. It caused water levels in the city to rise rapidly through the night.
The LTVCA is now operating the 6th Street Dam and Pumping Station. This should protect the south end of the city of Chatham on McGregor Creek from flooding.
Water levels are still rising on the Thames River itself in the City of Chatham. Basements of the businesses along King Street in downtown Chatham could begin flooding at any time now.
The behavior of ice jam related flooding is very unpredictable. The last times there was ice jamming at Prairie Siding with somewhat similar flows in the Thames River, water levels in the city rose an additional 0.70 m from where they were at 10:00 a.m. This would create water levels similar to the 2008/2009 flood (not ice jam) or the 1984 flood (ice jam). However, there was a significantly greater thickness of ice during the 1984 ice jam flood. If such water levels are reached, this could put water on Siskind Court, William St at Water St., Salter St., and Thames Street at Pitt St.
Should conditions of the ice jam itself change, there could be additional impacts along the downstream portions of the river through the Raleigh and Dover areas and into the town of Lakeshore including Lighthouse Cover. Residents should pay close attention to local conditions and be prepared should water levels exceed the flood protections.
Residents in the south end of the city of Chatham should also pay attention to local conditions. Weather forecasts for the afternoon and evening are calling for 15-20 mm of rain with the potential for thunderstorms. As water levels are high, excessive rainfall could lead to localized flooding upstream in the areas along McGregor and Indian Creek currently protected by the 6th Street Dam.
People should take extra caution and avoid the river, ditches, and streams. The combination of slippery banks, broken or unstable ice and fast moving cold water can be dangerous. Standing water can also present its own unseen hazards. Children and pets and livestock should be kept away from the water.
Officials will continue to monitor the situation and update this advisory if necessary.