This diversion gate on Mill Creek is a challenge to manage and clean during spring floods like this one in 2017.

Image Credit: SUBMITTED/City of Kelowna

The City of Kelowna is about to take the first step in a six-year project to reduce the flooding risk for homes and businesses in the city's downtown.

The city got a $22 million federal government grant in 2019 to help cover the $55 million cost of improvements along Mill Creek. It runs east of the Kelowna International Airport, next to the Okanagan Rail Trail then through residential neighbourhoods before flowing into Okanagan Lake just south of the Bennett bridge.

The project will start with the renovation of the 35-year-old diversion gates that redirect water at peak times from Mill Creek into pipes running along Leckie Road to Mission Creek.

“That structure is an operational challenge every time freshet occurs in the spring so we’re doing some major upgrades to it,” Rod MacLean, the city’s utility planning manager, explained.

The diversion structure tends to get plugged with trees and other debris that gets pushed down into the water and reduces the flow through the diversion pipes. That can result in spikes of water causing damage downstream and can be difficult, even dangerous, to remove.

The first stage of the project will be to upgrade the concrete, raise the structure a bit and replace screens. A large “grizzly” rack will be moved further away from the structure and angled, so trees will rise upwards where they can be removed more easily and don’t impede the water flow.

A smaller screen will have brushes to automatically clear smaller debris away, MacLean said.

Later, work in the creek bed will allow a small pond to be created during peak water flows to slow it down so it’s more easily managed.

“It will never be perfect because of the confined space we have around there,” MacLean said.

The walkway on Mill Creek is seen during lower water in the fall of 2020.

Image Credit: SUBMITTED/City of Kelowna

This initial stage of the project will cost upwards to $5 million but there’s much more work to be done over the next six years, which is the time limit for the provincial grant money.

That work will include improvements along Mill Creek both upstream and downstream of the diversion structure.

There are no plans to significantly increase the amount of water that can be diverted to Mission Creek, but there will be some minor capacity increases, MacLean said.

READ MORE: Millions to be spent to keep Kelowna residents safe from Mill Creek

“We’re leaving that the way it is,” he said. “It would be a nightmare twinning it and we’re also dealing with flows on Mission Creek so we don’t want to be doing more than necessary.”

Instead, he’s looking at improving Brandt’s Creek as part of the overall project to carry some overflow when necessary.

Part of that work will likely include making Brandt’s Creek more natural through the city’s industrial North End.

READ MORE: UPDATE: Kelowna's Mill Creek spills over its bank, flooding apartment building, houses

“When it gets into the industrial area, it ceases to look like a creek. It’s more like a channelized ditch,” MacLean said. “We will create conditions where Brandt’s Creek looks more like a creek and has some fish bearing abilities.

"Everything we’re doing includes flood management, but also includes major upgrades to recover some of the fish passage and fish riparian conditions that have been lost over the years.”

The city is processing a development permit application for the diversion project with the expectation that the work will be done before next year’s spring freshet.

 — This story was updated at 11 a.m. Nov. 22, 2021, to indicate the grant was from the federal government and there will be some minor capacity increases to the flow of water to Mission Creek.

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