The city will postpone work on the middle Colliery Dam until 2023 while data is gathered to redefine extreme flood danger for the Chase River. (News Bulletin file photo)

Further work postponed on middle Colliery Dam

New study suggests extreme flood flows might be less likely than previously estimated

The city will postpone further work on the middle Colliery Dam until at least 2023 while more data is gathered on the Chase River.

In a press release issued Tuesday morning, the city said the completion of the lower Colliery Dam auxiliary spillway partially address outstanding requirements from the Provincial Dam Safety Section order, which also required the city to address safety risks at the middle dam.

The city reviewed flood and seismic risks for the middle dam. The new study suggests that extreme flood flows through the middle dam might be lower than previously estimated.

“This new analysis takes advantage of river level data that wasn’t previously available,” said Poul Rosen, city senior manager of engineering, in the press release. “The additional data gained by continuing to monitor river levels will provide more certainty of the results and ensure that any future decisions on the middle dam can be made with confidence.”

The study looked at several years of river level data gathered through the early warning system installed at the dams in 2014 to make predictions about extreme flood events and also compared runoff rate data from other watersheds in the region to provide the basis for the decision to defer further risk assessment until 2023.

“Since this new model only uses a few years worth of data, it is not possible to make definitive predictions about extreme events,” Rosen said. “However, the lower flow results suggest that years of further data collection is warranted before any significant decisions are made or any potential future work at the middle dam planned.”

As a result of the study, the city and province agreed the best strategy regarding the middle dam will be to continue gathering river flow data for a hydrology model update in 2022.

For more information on the Colliery Dams visit

Just Posted

Three strong earthquakes reported off Vancouver Island

The quakes, all measuring more than 6.0 on the richter scale, were about 260 kilometres west of Tofino

OPINION: Nanaimo not only voted, but voted with purpose

Nanaimo’s civic leadership will see the change that so many wanted

Explosion at homeless camp causes brush fire along Millstone

Nanaimo Fire Rescue crews haul hundreds of metres of hose down ravine

New Nanaimo Ladysmith school board will need to get its bearings

Trustee candidates waited till midnight Saturday for election results, but say the wait was worth it

2018 municipal election: Few surprises on Vancouver Island

16 incumbent mayors will continue in their positions for four more years

ELECTION DAY: Krog voted in as Nanaimo’s next mayor

Hemmens, Armstrong, Geselbracht, Brown, Turley, Bonner, Thorpe and Maartman elected as councillors

Voting set to start in B.C. proportional representation referendum

Two-part ballots now being mailed to all registered voters

B.C. oncologist changing the face of breast cancer treatment

Dr. Juanita Crook, a Kelowna oncologist, has seen 100 per cent success using brachytherapy to treat breast cancer in some patients.

B.C. Youtuber to seal himself ‘in a jar’ to demonstrate impacts of climate change

Kurtis Baute wants to see how long he can last in a 1,000 cubic foot, air-tight greenhouse

One of Taiwan’s fastest trains derails, killing at least 18

The train was carrying more than 360 people

Scheer marks one-year countdown to federal election with campaign-style speech

Conservative Leader insists that it will be Justin Trudeau who ‘makes it personal’

Canada Post union announces rotating strikes in four Canadian cities

Mail will still be delivered but it will be delayed

B.C. VIEWS: Residents have had enough of catering to squatters

Media myth of homeless victims offends those who know better

B.C. man sets new Canadian marathon record at Toronto Waterfront Marathon

Cam Levins ran it in two hours nine minutes 25 seconds

Most Read