BC Hydro will be testing the sirens along the Puntledge River on May 7 and May 9.
Whether planned or unplanned, quick river flow adjustments can be a public safety hazard, so the BC Hydro warning sirens placed along the river from the Comox Dam to Puntledge Park must initiate.
Permanent river safety signage is in place, but the siren system provides notice of a real-time flow event and for people to move out of the river. The water flow siren system test is done once a year.
BC Hydro will be manually testing the siren system on May 7, from approximately 8 a.m. to 4 p.m., prior to the actual river flow tests on May 9.
“On May 9, we advise the public to stay out of the Puntledge River given the flow tests and the siren activations that will be taking place,” said Stephen Watson, of BC Hydro. “Temporary caution and danger safety signage will be placed along the river from Comox Dam to Condensory Bridge. BC Hydro staff will also be along the river to monitor the warning system. Depending on the test results on May 7, there is a chance a few sirens may be modified and briefly tested again on May 8.
“On May 9 the generation station will likely still be running at about 20 per cent of capacity, and we will shift some water flow through the Nymph Falls and Stotan falls section of the river, where flows will go from about 6 m3/s to about 20 m3/s. This flow redirection is to keep fish habitat fully covered and limit any potential impacts to fish from the test. After 8 a.m., there will be a quick pulse release from the Comox Dam to increase the river flow by an additional 20 m3/s. This flow should then initiate the siren at the dam and as the water surcharge moves downstream, with the other sirens initiating in sequence. For the last part of the testing, the flow out of the generating station will be increased quite rapidly to test the siren just downstream of the station.”
The current discharge from the Comox Dam is about 20 cubic metres per second (m3/s). At various times on May 9 the Puntledge River flow will increase to 27 m3/s and hit a brief peak of about 50 m3/s.
“We know people enjoy the Puntledge River yet this test is also a reminder that this is a hydroelectric system where river flows may change quickly,” said Watson. “With the warmer weather, people will begin to gravitate to water to cool off and enjoy the summer. About 500 people have been counted throughout the Puntledge River system at one time.”
The Puntledge River hydroelectric system includes the Comox Dam, which impounds the Comox Lake Reservoir, where the water released travels 3.7 kilometres down to the Puntledge River Diversion Dam. From there, a minimum fish habitat flow is provided down the river and the majority of water is directed down a five-kilometre penstock to the generating station, where the water is then discharged back into the river. River flow hydraulics and under-surface currents can be dangerous. Only 15 centimetres of fast flowing water is enough to knock a person off their feet.