The City of Hamilton states in a written memo that a two-day water service disruption affecting Stoney Creek plateau residents on May 20 and 21 was caused by the recommissioning of a 90-inch transmission line, and not related to the ongoing strike of 55 unionized Hamilton Water employees.
The Stoney Creek plateau is the area between Highway 8 and the escarpment, and between Green Road and Regalview Drive, and is elevated “approximately halfway up the escarpment.”
The 90-inch transmission line is Hamilton’s largest watermain. It connects the Woodward Avenue water treatment plant to the Greenhill Avenue reservoir. The reservoir provides water for nearly the entire lower city from Bayfront Park in the west to Fifty Road in the east.
The line was taken out of service in March for emergency repairs.
In the memo signed by Nick Winters, the City states that in advance of recommissioning the 90-inch line, water levels in three reservoirs (Kenilworth, Greenhill, and Dewitt/Ben Nevis) “were all strategically lowered” “to promote the movement of fresh water throughout [the lower city water] district during the recommissioning process.”
“This prevents water from aging in the system and minimizes the risk of water quality issues across the city.”
The City states “There was no way to know for certain who, if anyone, in this large area may experience a temporary change in their water service (water pressure or water quality) during the work to recommission the 90-inch Woodward/Greenhill transmission main.”
The Lower Pressure Event
The memo states:
“At approximately 11:00 a.m. on May 20, 2025, the Dewitt/Ben Nevis reservoir level dropped to approximately 1.2 metres, at which point the pumps could no longer function properly and had to be shut down (see Appendix B). This caused the pressure in the Stoney Creek plateau area to drop to approximately 26 psi, where it remained until approximately 9:00 p.m. on May 20, 2025, at which time the reservoir level had increased sufficiently for the pumps to be restarted. After the pumps restarted, the pressure in the Stoney Creek plateau area increased to approximately 43 psi.”
“Records from the [Dewitt/Ben Nevis reservoir] pressure monitor confirms that while the water pressure did drop significantly, it was maintained at approximately 26 psi, and at no time was there a lack of water.”
The City received six low-pressure complaints and four water quality complaints from residents in the Stoney Creek plateau area.
Provincial Review of Event
The memo states the local district office of the Ministry of the Environment, Conservation & Parks (MECP) launched a review of the incident on May 28 as a result of media coverage. The water workers’ union claimed the event was related to the strike.
“On June 13, 2025, the MECP provided a written notification to Hamilton Water advising that no issues of non-compliance were identified during their review,” the memo signed by Winters states. “The MECP also provided some recommendations which focused on using lessons learned to inform future operational and emergency planning.”
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v. 1.0.0
Published: June 17, 2025
Last updated: June 17, 2025
Author: Joey Coleman
Update Record
v. 1.0.0 original version