BC Hydro studying how to respond to sudden water discharge below Puntledge River dam

BC Hydro warns the public to be cautious in the Puntledge River from the Puntledge diversion dam to the generating station.

BC Hydro is issuing a public safety notice to be cautious within the Puntledge River from the Puntledge diversion dam to the generating station.

This five-kilometre stretch includes areas like Barber’s Hole, Nymph Falls and Stotan Falls. The river base flow will be increased by about threefold for Thursday and Friday so BC Hydro can conduct some river flow tests. River flows below the generating station will slightly increase but will be within normal ranges.

BC Hydro has initiated a project to respond to the risk of a sudden water flow discharge below the diversion dam, just upstream of Barber’s Hole. The project was initiated earlier this year to deal with just such a risk that happened last week.

On May 27 in the early evening, the Puntledge River generating station was forced offline due to an equipment malfunction. The water bypass facility, used to quickly switch over water flows from the turbine to maintain river flow continuity downstream, opened but complications arose when attempts were made to transfer the water back to restart the generating unit.

This meant that about 25 cubic metres per second (m3/s) of water that was entering the pipeline five kilometres upstream was then blocked and forced over the diversion dam and down the Puntledge River.

Base fish habitat flows of about 6 m3/s increased at a fairly high rate and was a public safety risk downstream. BC Hydro’s siren system immediately initiated to warn people to move out of the river before the water moved downstream.

The Browns River was flowing high that day from rain so river flows downstream of the generating station were good and covered fish habitat despite water flows out of the generating station being curtailed.

BC Hydro reduced the discharge from the Comox Dam until the generating station went back into service on May 28.

BC Hydro communicated with the Ministry of Forest, Lands, and Natural Resource Operations, Fisheries and Oceans Canada, and the Comox Valley Regional District. BC Hydro believes there were minimal impacts to fish, and the CVRD’s domestic water supply withdrawal system was unaffected.

This is a reminder for the public to be cautious in the Puntledge River, particularly the area of Barber’s Hole, which BC Hydro considers as having the highest safety risk. Please obey safety signage and siren notification.

This Thursday and Friday, BC Hydro staff and consultants will take river flow readings, for depth and velocity, to better understand river flow conditions from the diversion dam to the generating station. The river flow increase will happen Wednesday night.

This information will help further develop project considerations. BC Hydro will communicate to the community over the next 12 to 16 months some conceptual options to alleviate or significantly reduce safety risks.

— BC Hydro

 

Comox Valley Record