Flood Watch – Inland Lake & River Flooding – May 5, 2025

Hamilton Conservation Authority (HCA) is advising that water levels and flows in all watercourses within the HCA watershed are expected to increase significantly as a result of the forecasted rain and potential thunderstorms for today (May 5). Significant water safety concerns, as well as localized watercourse flooding of low-lying areas that typically flood during higher water levels, is expected.

Significant watercourse flooding also has the potential to occur.

There is considerable uncertainty as to the amount of rain and runoff that will occur. HCA staff continue to monitor watercourse, watershed, and weather conditions closely.

A close watch on local conditions is recommended. Also, HCA wishes to remind residents to use caution near all water bodies and structures such as bridges, culverts and dams during this time. Above normal water levels, faster moving water, rapidly changing levels and flows, and slippery banks may pose significant hazards. Adults are advised to keep children and pets away from water bodies at this time.

Today (May 5), the Hamilton area is expected to receive between 10 and 48 mm of total rain (this includes 10 to 23 mm of rain, with an additional 5 to 25 mm possible if thunderstorms occur). On Tuesday (May 6), the Hamilton area is expected to receive between 0 and 11 mm of rain. Then on Wednesday (May 7), the Hamilton area is expected to receive between 0 and 17 mm of total rain (this includes 0 to 7 mm of rain, with an additional 5 to 10 mm possible if thunderstorms occur).

Current water levels and flows in watercourses within the HCA watershed are near baseflows to slightly elevated above baseflows, and do not pose significant water safety concerns nor significant watercourse flooding concerns.

This message is in effect until Wednesday, May 7, 2025, at 4:30 pm, when it will either be updated or cancelled. HCA will issue updates before May 7 as needed. This message replaces the Flood Watch – Inland Lake and River Flooding message issued on April 30, 2025

There are no other active messages at this time.

For further information or questions regarding this message, please contact:
Jonathan Bastien, Water Resources Engineer
Phone: 905-525-2181 ext 138
Jonathan.Bastien@conservationhamilton.ca

Flood Watch – Inland Lake & River Flooding – May 5, 2025

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Current Water Levels

Water Level Explanations

Flood Status Explanations

	Normal No low water conditions exist.
	Level 1 Water users are asked to voluntarily reduce consumption by 10 percent. Precipitation totals are less than 80 percent of long-term averages and/or 30-day average streamflows are less than 100 / 70 percent (springtime / otherwise) of the minimum of the long-term average monthly flows for summer months.
	Level 2 Water users are asked to voluntarily reduce consumption by 20 percent. Precipitation totals are less than 60 percent of long-term averages and/or 30-day average streamflows are less than 70 / 50 percent (springtime / otherwise) of the minimum of the long-term average monthly flows for summer months.
	Level 3 There is also potential for economic harm to water takers and/or significant harm to the ecosystem. The Hamilton Water Response Team may ask the province to impose mandatory restrictions on those holding Permits to Take Water. Precipitation totals are less than 40 percent of long-term averages and/or 30-day average streamflows are less than 50 / 30 percent (springtime / otherwise) of the minimum of the long-term average monthly flows for summer months.

	Normal No flood conditions exist.
	Watershed Conditions Statement - Water Safety High flows, unsafe banks, melting ice or other factors that could be dangerous for recreational users such as anglers, canoeists, hikers, children, pets, etc. Flooding is not expected.
	Watershed Conditions Statement - Flood Outlook Early notice of the potential for flooding based on weather forecasts calling for heavy rain, snow melt, high wind or other conditions that could lead to high runoff, cause ice jams, lakeshore flooding or erosion.
	Flood Watch Flooding is possible in specific watercourses or municipalities. Municipalities, emergency services and individual landowners in flood-prone areas should prepare.
	Flood Warning Flooding is imminent or already occurring in specific watercourses or municipalities. Municipalities and individuals should take action to deal with flood conditions. This may include road closures and evacuations.