Why does it flood so often in New Hamburg?

A park gazebo in downtown New Hamburg is seen here under water when the Nith River flooded its banks recently following heavy rain and rapid snowmelt. Mike Grummett photo

By Lee Griffi

Anyone who lives in the New Hamburg area is well aware of the continuous flooding problem. The questions are why it happens and what, if anything, can be done about it?

New Hamburg is one of many communities known to be flood-damage centres in the Grand River watershed. A significant portion of the downtown core lies within the Nith River floodplain, making it susceptible to frequent flooding.

Communities along the Nith are more vulnerable in comparison to other communities within the Grand River watershed, in part because there is no multipurpose reservoir upstream to regulate flows like in other areas of the watershed.

“The GRCA (Grand River Conservation Authority) maintains the dike in New Hamburg, which provides flood reduction during more frequent, smaller events. Maintenance of this dike is part of the GRCA’s water-control structures program,” said Serena Catania, GRCA’s supervisor of communications and marketing.

“That said, it’s important to note that while the GRCA’s dikes and dams help manage river flows and reduce the impacts of flooding for downstream communities, this flood-management infrastructure cannot eliminate the risk of flooding.”

There are different causes of riverine flooding. A rapid rise in temperatures or rainfall, or a combination of the two, can generate runoff and cause riverine flooding. Ice in a river or stream can also pile up in a location and create an ice jam, which can cause flooding. 

The GRCA manages the risk of flooding by monitoring weather conditions and river flows to know when flooding is possible, issuing flood messages to alert municipal flood coordinators and the public about coming high water, and operating seven multipurpose dams and reservoirs to hold water and reduce flood peaks.

“We own and maintain dikes to protect low-lying areas in Kitchener (Bridgeport), Cambridge (Galt) and Brantford, and we regulate development in flood-prone areas to reduce potential property damage,” Catania said.

The GRCA completed a flood mitigation study for New Hamburg in 2019 and 2020. The project provided an updated estimate of average annual flood damage, a preliminary review of options to reduce flood risk, and an initial cost-benefit analysis to determine the feasibility of potential options.

“One of the low-cost options identified included vegetation removal in the floodplain to improve the passage of water during a flood event. (We) have been completing this work over the past few years, and updated floodplain modelling and mapping for the Nith River was also completed as part of the study,” said Catania, who added public consultation took place at that time.  

On Monday, the province provided an update on its plan to reduce the number of conservation authorities from 36 to nine regional groups. The plan follows consultations on how conservation authorities can help get shovels in the ground faster on housing and other local infrastructure projects, while strengthening their role in managing watersheds and protecting communities from flooding and natural hazards. 

The province says the regional approach will reduce administrative duplication, redirect resources to frontline conservation and modernize permitting. If amendments to the Conversation Authorities Act are approved, the transition is expected to be completed early next year. 

The chair of the GRCA was quick to provide a statement.

“The Ontario government has announced the next step in its plan to reform the province’s conservation authority system and its intention to create nine regional conservation authorities. Based on the extensive feedback received, the province has amended the boundaries that were proposed in the ERO posting in 2025,” said GRCA chair John Challinor II.

“Under the revised plan released on March 10, the Grand River Conservation Authority will be part of the Eastern Lake Erie Region Conservation Authority. We appreciate that the province considered the GRCA board’s feedback in proposing a more balanced, rightsized model that includes the GRCA.”

Challinor II explained the GRCA will continue to review provincial information as it becomes available, and updates will be provided on its website. A preliminary report will be included in the March 27 board meeting agenda.

“The (board) supports the government’s goals of modernizing the conservation authority system by enhancing consistency, efficiency and technical capacity across Ontario’s conservation authority system. We remain committed to working collaboratively with the province, the Ontario Provincial Conservation Agency and our municipal partners, while maintaining our focus to protect people and property from floods and other natural hazards, improve the health of the Grand River watershed, and connect people with the environment.”

Residents of New Hamburg are encouraged to refer to a guide on the GRCA’s website for information regarding flood preparedness, flood warning zones and what to do when flooding is imminent or occurring.

“Homeowners and businesses can prepare for and mitigate flood impacts on their property by flood-proofing their properties, leaving basements unfinished, bringing belongings up to main floors and having an emergency plan.”

The GRCA manages flood risk in the area by monitoring weather conditions and river flows in the Nith, and we use this information to issue flood messages to the Waterloo Regional Police and the Wilmot Township flood coordinator.

More information can be found at www.grandriver.ca/our-watershed/flooding/flood-warning-system/.